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passive hubs for fieldbus networks MEGABLOCK SERIES reliable interconnection for fieldbus networks Megablocks are DIN rail mounted passive hubs for Foundation Fieldbus networks. They connect several field devices to the network trunk cable and provide short circuit and surge protection to the segment. Megablocks minimize hand wiring and allow individual devices to be added to and removed from the segment without disrupting network communication. A green power LED on each unit indicates whether at least 9V of DC power is present. Megablocks are available in four and eight drop versions. Multiple Megablocks are easily wired to one another to allow larger segments to be constructed. The Megablock Terminator is easily wired to any Megablock to prevent signal reflection on the fieldbus segment. The Megablock Terminator is clearly marked for easy identification by field personnel. The Megablock 8 and Megablock Terminator are ideal for a star or chickenfoot topology where several transmitters are connected at a single field junction box. Occupying approximately the same junction box space as conventional 4-20 mA wiring, Megablocks are ideal for both retrofit and greenfield installations. Each Megablock has two dedicated connections for the fieldbus home run or trunk cable. Trunk connections are easily identified by their black connectors. Separate numbered connections are provided for each spur drop. Connections to the Megablock are made using pluggable screw terminal type connectors. This allows wire terminations to be made to the individual connectors which are then plugged into the Megablock. Devices can then be easily connected and disconnected during commissioning. After commissioning, retaining screws are tightened to secure each connector to the Megablock. To minimize susceptibility to single points of failure, Megablocks are available with built-in SpurGuard™ short circuit protectors which prevent a short circuit in any of the individual transmitters or spur cable runs from bringing the entire fieldbus segment down. A red LED near each spur connection indicates that a spur is shorted and is in overcurrent mode. To protect field transmitters from damage due to induced voltages on the fieldbus cable, each Megablock has built-in differential surge suppression that is activated when the potential across the twisted wire pair exceeds 39 VDC. The Megablock Terminator has transient surge suppression that works by shunting excess current to ground when the shield to ground potential exceeds 75 VDC. Sect4c-1 SPECIFICATIONS MTL - RELCOM MEGABLOCKS Megablock products will be approved for; Class I, Division 1 and 2 and Zone 1 and 2 applications. For details see: www.relcominc.com/fieldbus Mounting Requirements: 35 mm DIN rail Wire Capacity: 12-24 AWG Case material: Lexan Polycarbonate Temperature Range: -45 to +70°C Voltage Required to activate Power LED: 9.2V minimum INSTALLATION Megablocks can be mounted vertically or horizontally using 35 mm DIN rail within a suitable enclosure, such as a field junction box. Megablocks are removed from the DIN rail using a flat blade screwdriver to release the mounting platform. Use of DIN rail end stops is recommended to prevent sliding in vertical installations. Four and eight port Megablocks have labeling areas so that segments can be easily identified according to plant standards. Megablocks with SpurGuards™ Power Consumption: No SpurGuards™ tripped: 1.7 mA per SpurGuard™ tripped: 60 mA Maximum Current Delivered to Spur: 58.0 ± 1.0 mA Trunk to Spur Voltage Drop (SpurGuard™ not tripped): Maximum: 1.2 V Typical: 0.4 V (17 mA device current draw) Basic Megablocks Power Consumption: 0.4 mA maximum Maximum Current Delivered to Spur: Not Limited Megablock Terminator Operating Temperature Range: -45 to +70°C Common Mode Voltage Limit: 39 V Transient Mode Voltage Limit: 75 V Shown above is an example of a common Fieldbus segment topology. Eight field devices are connected to an eight-drop Megablock, which is mounted in a field junction box. One trunk connector on the Megablock is wired to a Megablock Terminator and the other to the segment trunk cable that leads to the control room or marshalling panel where the power supply and second terminator are located. The Megablock Terminator in the field has a normally open connection to earth ground that closes when surge conditions are detected. GROUNDING To prevent ground loops, a fieldbus segment should only be grounded at one point. This is usually done by grounding the cable shield at the control room end of the segment. If a permanent segment ground connection in the field is desired, this can be achieved by wiring the shield terminal on one of the Megablock trunk connectors to a suitable earth ground instead of wiring it to the shield terminal on the Megablock Terminator. ORDERING INFORMATION Megablock Series 4-drop Megablock Part Number FCS-MB4 4-drop Megablock with integrated SpurGuard™ short circuit protection FCS-MB4-SG 8-drop Megablock FCS-MB8 8-drop Megablock with integrated SpurGuard™ short circuit protection FCS-MB8-SG Megablock Terminator FCS-MBT Accessories Heavy Duty DIN rail end stop 35 mm DIN Rail, 1 metre length Part Number FCS-A06 FCS-A01 Sect4c-2 Physical Network IEC61158-2 FOUNDATION™ Fieldbus H1 Profibus PA connection system for fieldbus networks FCS SERIES reliable interconnection for Fieldbus networks FOUNDATION™ Fieldbus H1 and Profibus PA are digital communication network protocols used in industrial process control. Unlike traditional 4-20 mA communications systems, fieldbus uses a bus topology with multi-drop wiring. While this offers opportunities for significant cost savings relative to the point-to-point wiring used in 4-20 mA systems, it also poses a risk to control system reliability and availability. Because transmitters on a fieldbus network may share a single cable run, a failure or short of any individual device has the potential to interrupt data communication across the entire bus segment. Such events can occur due to accidents or even during routine instrument maintenance. The Fieldbus Connection System (FCS series) includes all the components necessary to provide connection and termination of field devices to FOUNDATION™ Fieldbus H1 and Profibus PA network segments. All FCS wiring blocks have LED indicators for bus segment power, expansion blocks to allow easy expansion of the number of device connections and circuitry to limit voltage on the fieldbus wiring. The FCS blocks are available with pluggable, screw terminal or cage clamp connectors. The Fieldbus Spur Block, FCS-S series, provides four fieldbus cable connections. For example, the Spur Block can be used in the home run to attach two devices to the middle of the Fieldbus. Several Spur Blocks may be used on a fieldbus segment. When adding spurs to a fieldbus segment, the total maximum spur length must not be exceeded as defined by the IEC 61558-2 standard. Using a Spur Block allows the removal of a device cable from the fieldbus without affecting other devices or the integrity of the segment wiring The grounded Terminating Block, FCS-TG, is used as a terminator and wiring block at the control room end of the fieldbus. It interconnects up to four shielded wire pairs. For example, the home run cable, the DCS, the fieldbus power supply, and one device. It contains a high quality interconnection socket that expands the number of devices which may be attached to the control room end of the segment (see Expansion Block). It provides a connection from earth ground to the shields of the fieldbus cables via the ground stud. The shield should only be grounded at one point on each segment to prevent groundloop currents in the system. The grounded Terminating Block is easily identified by its black housing cover. Only one grounded Terminating Block is used on each fieldbus segment. The FCS-TG requires the use of a separate fieldbus power supply. The isolated Terminating Block, FCS-TI, is used as a terminator and wiring block at the far end of the segment, sometimes called the chicken foot. It interconnects up to four shielded wire pairs; for example, the home run cable and three devices. It contains a high quality interconnection socket that expands the number of devices which may be attached to the chicken foot (field) end of the segment. Surge suppressers are built into the isolated Terminator to protect the devices attached to the fieldbus from near lightning strikes. A stainless steel ground stud is used for earthing the induced surge currents. When not discharging surges, the ground stud is isolated from the shielding of the Terminator and the wires as required by the fieldbus standard and for intrinsic safety considerations. Except for its grey housing, it appears identical to the grounded terminator. The Expansion Blocks plug into either a Terminator, a Spur Block, or into each other so that wiring between blocks is eliminated. As many Expansion Blocks as needed may be used on a fieldbus segment. The expansion connectors can also be used for test equipment or handheld devices for temporary connection to the fieldbus. The Expansion Block eliminates inter-terminal block wiring or having to put more than one wire into a wire terminal. FCS series wiring blocks can be mounted vertically or horizontally within a suitable enclosure, such as a field junction box. They can be mounted directly or by using 35 mm DIN rail. They are secured to DIN rail by two extendable locking tabs. DIN rail end stops are recommended to prevent sliding in vertical installations. Sect 4c-3 MTL - RELCOM FIELDBUS TERMINATOR FCS-T SERIES DESCRIPTION The Isolated Terminating Block, FCS-TI series, is used as a terminator and wiring block at the far end of the segment, sometimes called the chicken foot. It interconnects up to four shielded wire pairs. For example, the home run cable and three devices. A high energy surge suppressor built into the isolated Terminator protect the devices attached to the fieldbus from near lightning strikes. A stainless steel ground stud is used for earthing the surge currents induced into the shields of the fieldbus wiring. When not discharging surges, the ground stud is DC isolated from the cable shields. Except for its grey housing, it appears identical to the grounded terminator. Only one isolated Terminating Block is used on each fieldbus segment. The Grounded Terminating Block, FCS-TG series, is used as a terminator and wiring block at the control room end of the fieldbus. The Terminator interconnects up to four shielded wire pairs. For example, the home run cable, a DCS, a fieldbus power supply, and one device. It provides a connection from earth ground to the shields of the fieldbus cables via the ground stud. The shield should only be grounded at one point on each segment to prevent groundloop currents in the system. The grounded Terminating Block is easily identified by its black housing cover. Only one grounded Terminating Block is used on each fieldbus segment. Both Terminators have a built-in differential surge suppressor that limits spikes which may be present on the fieldbus. This protects attached devices from damage. The Terminators can also be expanded with Relcom Fieldbus Expander blocks, FCS-E series, to provide four additional device connections. The Terminators have an LED that illuminates to indicate when segment power is present. APPLICATION Fieldbus devices are connected to the Terminator with shielded twisted pair fieldbus cable. Up to four connections may be made at the Terminator. The connections are typically one homerun cable and one, two, or three device cables. A controller or DCS is considered to be a "device". To prevent "ground loop currents" only one point on each segment should be grounded. If a Grounded Terminator and an MTL Power Conditioner are used on the same segment, only one of them should be grounded. The bolt on the Isolated Terminator should ALWAYS be grounded. The Terminator may be mounted on a flat surface with screws or on a 35mm DIN rail using the integrated sliding tab. See the package outline for additional mounting and dimensional details. SPECIFICATIONS All FCS-TI and FCS-TG Series: Terminator: 100 ohm 1%, 1 µF 50 V Operating Temperature: -45 C to +70 C LED Current: 3 mA maximum (at 32 Volt segment power) Expansion connector: One set female (gold plated) Wire Capacity: 12-24 AWG Case material: ABS plastic Weight: 105 g FCS-TI-PL, FCS-TI-ST, and FCS-TI-CC: Surge Limit Start: 39 Volts (differential) Surge Limit (Hard): 43 Volts (differential) Surge Capacity: 10,000 ampere µs (lightning) Sect 4c-4 FCS-TG Fieldbus Power Supply HOST O + G S B O + G S B - + S + S - O G B O G B Grounded Terminator Block Device 2 O + G S B O + G S B - FCS-S + S + S - O G B O G B + S + S - O G B O G B Device 1 Homerun Device 3 Spur Block Homerun FCS-TI Device 6 O + G S B O + G S B - Device 4 Device 5 Isolated Terminator Block SAMPLE TOPOLOGY The topology above illustrates a fieldbus segment. If additional fieldbus devices need to be added, Expansion Blocks (FCS-E) can be plugged into any of the FCS wiring blocks to increase the number of fieldbus connection points by four (4) for each Expansion Block used. The shields of the segment wiring are grounded by attaching the bolt on the Grounded Terminator to ground. Grounding the bolt on the Isolated Terminator Block provides protection from shield currents induced by near lightning strikes but does not provide a connection to ground under normal operating conditions. MTL - RELCOM FIELDBUS EXPANDER FCS-E SERIES DESCRIPTION Fieldbus Connection System blocks can be expanded for additional wire pair connections by using the Expander Block, FCS-E. Each Expander Block provides four more cable connection points. The Expander Block plugs into a Terminator, Spur Block or into another Expander block so that wiring between blocks is eliminated. As many Expander Blocks as needed can be used on a fieldbus segment. The Expander Block has an LED which illuminates to indicate bus power is present. FCS-TG HOST FCS-TI The Expander Block simply plugs into other Relcom wiring blocks and into other Expander blocks. All Relcom fieldbus blocks may be mounted with screws to a flat surface or snapped onto a 35mm DIN rail. See Package Outline for dimensions and mounting information. If the Expander Block is to be mounted on a DIN rail, an end stop, FCS-A02, should be used to prevent separation of the plugged modules. SPECIFICATIONS Wire Capacity: Case material: Weight: Device 2 Device 3 O G B O G B Isolated Terminator Block O + +O G S S G - B B O + +O G S S G - B B O + G S B O + G S B - Device 5 Device 8 FCS-E -45 to +70°C 3 mA max. at 32 VDC 39 Volts 43 Volts One set female One set male (gold plated) 12-24 AWG ABS plastic 95 g + S + S - Grounded Terminator Block APPLICATION Temperature Range: LED Current: Surge Limit Start: Surge Limit (Hard): Expansion connectors: O + G S B O + G S B - Fieldbus Power Supply + S + S - O G B O G B Device 1 Homerun Device 4 Device 6 Device 7 Expansion Block SAMPLE TOPOLOGY In the example above, the power supply and one terminator are located at one end of the segment (usually near the control room). The home run or trunk cable runs into the field and connects to a field junction box. There, the home run cable is connected to a wiring block (FCS-T series) that contains the second terminator for the segment. This configuration alone would allow for connection of three device spurs. With the addition of one Expander block (FCS-E series) the number of device spurs available on the segment is increased to seven. Two expander blocks would bring the total to 11 devices. Sect 4c-5 MTL - RELCOM FIELDBUS SPUR BLOCK FCS-S SERIES DESCRIPTION The Fieldbus Spur Block, FCS-S series, provides four fieldbus cable connections. For example, the Spur Block can be used in the home run to attach two devices to the middle of the fieldbus. Several Spur Blocks may be used on a fieldbus segment. When adding spurs to a fieldbus segment, the total maximum spur length must not be exceeded as defined by the ISA SP50.02 standard. Using a Spur Block allows the removal of a device cable from the fieldbus without affecting other devices or the integrity of the segment wiring. The Spur Block can also be expanded with the Relcom Fieldbus Expander Block to provide four additional device connections. The Spur Block has an LED that illuminates to indicate when segment power is present. A built-in differential surge suppressor limits spikes that may be present on the fieldbus and protects attached devices from damage. Spur Blocks are available with pluggable (FCS-S-PL), screw terminal (FCS-S-ST), or cage clamp connectors (FCS-S-CC). FCS-TG O + G S B O + G S B - Fieldbus Power Supply HOST O G B O G B Grounded Terminator Block O + G S B O + G S B - Device 2 FCS-S + S + S - O G B O G B + S + S - O G B O G B Device 1 Homerun Device 3 Spur Block Homerun FCS-S APPLICATION Fieldbus devices are connected to the Spur Block with shielded twisted pair fieldbus cable. Up to four connections may be made at the Spur Block. The connections are typically two homerun cables and one or two device cables. The Spur Block may be mounted on a flat surface with screws or on a 35mm DIN rail using the integrated sliding tabs. See the package outline on the next page for additional mounting and dimensional details. O + G S B O + G S B - Device 5 -45 to +70°C 3 mA max. at 32 VDC 39 Volts 43 Volts One set female (gold plated) 12-24 AWG ABS plastic 95 g Device 4 Spur Block FCS-TI Device 6 SPECIFICATIONS Temperature Range: LED Current: Surge Limit Start: Surge Limit (Hard): Expansion connector: Wire Capacity: Case material: Weight: + S + S - Device 7 Isolated Terminator Block O + +O G S S G - B B O + +O G S S G - B B O + G S B O + G S B - Device 9 Device 11 FCS-E + S + S - O G B O G B Homerun Device 8 Device 10 Device 12 Expansion Block SAMPLE TOPOLOGY The topology shown above uses a power supply at the control room end of the fieldbus segment. If fieldbus devices need to be in or near the control room, an Expander Block can be plugged into the terminator wiring block to expand the number of fieldbus connection points by four (4). The shields of the segment wiring are grounded by attaching the ground bolt on the grounded terminator block to ground. Grounding the bolt on the Isolated Terminator Block provides protection from shield currents induced by near lightning strikes but does not provide a connection to ground under normal operating conditions. Sect 4c-6 MTL - RELCOM ORDERING INFORMATION FCS SERIES FCS PACKAGE OUTLINE (Ground/surge connection bolt and Male expansion connector not shown) 79.4 mm, 3.125" 1 S S 2 35 mm, 1.4" FCS-T Series Terminator Block with surge suppression and cage clamp connectors Part Number FCS-TI-CC 3 S Terminator Block with surge suppression and pluggable screw terminal connectors (SpurGuard™ compatible) FCS-TI-PL 92 mm, 3.6" Terminator Block with surge suppression and screw terminal connectors FCS-TI-ST Terminator Block with permanent connection of cable shield to ground and cage clamp connectors FCS-TG-CC Terminator Block with permanent connection of cable shield to ground and pluggable screw terminal connectors (SpurGuard™ compatible) FCS-TG-PL Terminator Block with permanent connection of cable shield to ground and screw terminal connectors FCS-TG-ST FCS-S Series Spur Block with cage clamp type connectors Part Number FCS-S-CC Spur Block with pluggable screw terminal connectors (SpurGuard™ compatible) FCS-S-PL Spur Block with screw terminal connectors FCS-S-ST FCS-E Series Expander Block with cage clamp connectors Part Number FCS-E-CC Expander Block with pluggable screw terminal connectors (SpurGuard™ compatible) FCS-E-PL Expander Block with screw terminal connectors FCS-E-ST Accessories 35 mm DIN Rail, 1 metre length DIN rail end stop Part Number FCS-A01 FCS-A02 S 4 5 mm, 0.2" Dia. 34 mm, 1.34" 35 mm 35 mm DIN Rail Mounting tabs expanded Sect 4c-7 overcurrent protection for fieldbus networks SPURGUARD™ SERIES cost effective interconnects for fieldbus networks ◆ 20 and 40mA versions ◆ overcurrent protection ◆ US patent pending ◆ standard DIN rail mount Sect 4c-8 FOUNDATION™ FieldbusH1 and Profibus PA are digital communication network protocosl used in industrial process control. Unlike traditional 4-20 mA communications systems, fieldbus uses a bus topology with multi-drop wiring. While this offers opportunities for significant cost savings relative to the point-to-point wiring used in 4-20 mA systems, it also poses a risk to control system reliability and availability. Because transmitters on a fieldbus network may share a single cable run, a failure or short of any individual device has the potential to interrupt data communication across the entire bus segment. Such events can occur due to accidents or even during routine instrument maintenance. A SpurGuard™ is a current-limiting device that provides short circuit protection to the fieldbus segment. By attaching a SpurGuard™ at each point where a field transmitter attaches to the segment home run cable, isolation of the network from individual device failures is achieved. A red LED indicates when a SpurGuard™ is providing overcurrent protection. SpurGuards™ are part of the Relcom Fieldbus Connection System (FCS-series) and are intended to work with any DIN rail mounted FCS wiring block that uses removable (pluggable) connectors. SpurGuards™ are available in current ratings of 20 and 40mA (plus ~ 30 mA safety buffer) to match the requirements of specific field transmitters. MTL-RELCOM SPURGUARDTM SPURGUARD™ SELECTION Because SpurGuards™ draw power from the segment when in short circuit mode, their short circuit current consumption must be taken into account during segment design. Use of SpurGuards™ with the lowest possible current consumption is recommended. This prevents excessive power from being drawn from the segment under short circuit conditions. To determine the SpurGuard™ for your application, add the nominal current requirement of the field device connected to the spur, 10mA of signaling current, and overhead to allow for temperature variations and the possible attachment of bus-powered test equipment to the spur. If the total current requirement is 50mA or less, the FCS-SG-20 is recommended. INSTALLATION SpurGuards™ are connected at each point where a spur attaches to the segment trunk. This is done by connecting the twisted pair cable that leads to the field transmitter to the SpurGuard™ which is then plugged into a Relcom FCS wiring block attached to the trunk. SPECIFICATIONS Short Circuit Current Limit* -40°C 20°C 50°C FCS-SG-20 60mA 52mA 47mA FCS-SG-40 91mA 78mA 71mA *The current limit decreases under prolonged short circuit conditions due to heating of SpurGuards™. Voltage Drop Trunk to Spur (SpurGuard™ not tripped): Maximum: 0.9 V Typical: 0.2 V (17 mA device current draw) Temperature Range: Wire Capacity: Case material: Weight: Dimensions: -40 to +70°C (ambient still air) 12-24 AWG Lexan Polycarbonate 9g 15.2 × 13.7 × 29.2 mm 0.600" 15.2mm 0.540" 13.7mm + S MOUNTING REQUIREMENTS SpurGuards™ require the use of Relcom FCS wiring blocks with pluggable connectors: FCS-S-PL, FCS-E-PL, FCS-TI-PL, or FCS-TG-PL. FCS wiring blocks are installed within a suitable enclosure, such as a field junction box, and are mounted using 35mm DIN rail. Flat panel installation is possible using the provided mounting screw holes. Voltage Limitations (at 70°C ambient still air) To prevent overheating under prolonged short circuit conditions, observe the following voltage* limitations: FCS-SG-20 31.0 VDC FCS-SG-40 19.5 VDC *The voltage present at a SpurGuard™ is a function of the power supplied to the segment, the load on the segment, and the length of cable separating the power supply from each SpurGuard™. See the Relcom Fieldbus Wiring Design and Installation Guide for detailed instructions on calculating power distribution on a Fieldbus segment. WARNING: Under prolonged short circuit conditions, SpurGuards™ may achieve surface temperatures in excess of 100°C. Use appropriate personal protective equipment when handling a SpurGuard™ that is, or has recently been, in short circuit mode. Short circuit mode is indicated by the red LED on each SpurGuard™. 0.860" 21.8mm 1.150" 29.2mm ORDERING INFORMATION SpurGuard™ FCS-SG-20 FCS-SG-40 Wiring Block FCS-S-PL FCS-E-PL FCS-TI-PL FCS-TG-PL Description SpurGuard™ for 20mA field devices (short circuit current limit = ??mA) SpurGuard™ for 40mA field devices (short circuit current limit = ??mA) Description Fieldbus Spur Block with pluggable connectors Fieldbus Expander Block with pluggable connectors Fieldbus Terminator with surge suppression and pluggable connectors Fieldbus Terminator with permanent cable shield to ground connection and pluggable connectors Sect 4c-9 live troubleshooting for FOUNDATION™ Fieldbus H1 networks The Fieldbus Monitor, FBT-3 is used to examine the operation of a live FOUNDATION™ Fieldbus network without interfering with its operation. The monitor is intended for maintenance personnel to verify network operation or to troubleshoot an errant network. The Fieldbus Monitor allows the user to quickly assess the health of a fieldbus network segment by providing measurements of bus power level, minimum signal level, and peak and average noise level. It also displays the number of devices present on the segment and indicates when devices are added or removed from the network. The Fieldbus Monitor is palm-sized for portability and is powered by the fieldbus so that no batteries or external power source is required. It includes color-coded test leads and an LCD display. Operation The FBT-3 can be connected to the network using the clip leads. The test leads are polarity sensitive and the Monitor will not operate if they are reversed. When first connected to a fieldbus, a Version number is displayed for 1 second. The MODE button is used to select from several network parameters that can be examined with the Monitor. When a function is selected, the LCD display reads “- - -” until the monitor has collected and processed the data. After that, the measured value is shown. The indication “OK” is shown if the measured value is within the acceptable range (as defined by the fieldbus specification). The rotating symbol in the lower right corner of the display indicates that there is network Sect 4c-10 FBT-3 FOUNDATION™ Fieldbus monitor activity. A horizontal bar under the rotating symbol indicates that a frame was detected, but could not be decoded. This is not a maintained function. I.e., if a single “bad” frame is detected, the horizontal underbar will only be on the display for a short time. Periodic “bad” frames will cause the underbar to blink. Following are more detailed explanations of each of the monitor’s modes: Power The DC voltage on the network is shown. Measurements over 9 volts are OK. The maximum displayed value is 25.5 volts. LAS If there is any activity on the network, the Link Active Scheduler (LAS) should be sending out Probe Node frames. The Monitor measures the signal level of the Probe Node frame. The signal level is in millivolts. Device If there are fieldbus devices active on the network, the Monitor counts them. If the count has remained the same since the Device function was selected, the display shows “OK”. Note that the LAS is considered a device and as such is included in the count. Devices are counted by watching their response to a Pass Token. If a device does not respond to the Pass Token, it is taken off an internal list and the count will be reduced. The device may still show up on PC monitoring software because the LAS will not take it off of the Live List until it has failed to respond to a Pass Token three times in a row. If a device leaves the network, “-” is displayed. If a new device is added, the display shows “+” Low The signal level of the device with the weakest signal is shown. The device’s address (hexadecimal) is displayed behind the word "LOW". This will be the lowest signal level reading from a device since the tester was connected to the fieldbus. Measurements greater than 150 mV are OK. Noise Av The noise on the network is measured during the silence between frames. The value is averaged over 10 measurements. Measurements of less than 75 mV are OK. Noise Pk The peak noise recorded since this function was started is displayed. Measurements of less than 75 mV are OK. New If a new device is to be added to the network, it must respond to the Probe Node frame sent by the LAS. The Monitor measures the signal level of the new device’s response. Measurements greater than 150 mV are OK. The address (in hexadecimal) of the new device is displayed also. Specifications The Monitor is powered by the fieldbus and draws approximately 10 mA of current from the network (depending on bus voltage and ambient temperature). The Monitor carries the CE mark and may be used in hazardous areas. Operating temperature range: 0-50ºC Dimensions: 12.9 × 7.0 × 3.1 cm Weight: 150 g monitoring of FOUNDATION™ Fieldbus networks FBT-4 fieldbus power and signal monitor The Fieldbus Power & Signal Probe, FBT-4, is used to examine the operation of a live FOUNDATION™ Fieldbus network without interfering with its operation. The Probe is intended for maintenance personnel to verify network operation or to troubleshoot an errant network. The Power and Signal Probe is designed to help instrument technicians quickly determine if bus power and signal levels are within specification at individual points on a fieldbus network segment. For example, if a fieldbus transmitter suddenly goes off-line, the FBT-4 can be used to determine if the problem resides in the transmitter itself or is due to an open or short in the network cable system. Inexpensive and portable, the FBT-4 runs on bus power and thus requires no batteries or other external source of power. Operation Connection One red and two green LEDs indicate the status of the fieldbus network. They are labeled Signal, Voltage, and Reversed. A lit green LED indicates that the network is performing satisfactorily. A lit red LED signals an error condition. Following are descriptions of the three indicators: Signal indicates that there is bus activity. It will only light if data traffic is detected with peak to peak amplitude greater than 150 millivolts. The validity of the data is not checked. You will notice that the LED blinks when there is bus activity. It is driven directly by the frame data and is thus not powered during the brief silence between packets. Voltage indicates that the DC Voltage on the fieldbus is greater than the 9.0 VDC minimum that is required by the fieldbus standard. Reversed indicates that the FBT-4 probes have been connected to the network incorrectly or that the fieldbus has been wired with reversed polarity. The pointed probe attached directly to the case of the FBT-4 is the negative input and should be connected to a negative point on the fieldbus. The red wire with the pointed probe should be connected at a positive point on the fieldbus. For hands-free operation, a red mini-hook assembly is available which can be attached to the end of the red pointed probe. A black cable with mini-hook is also available to plug onto the negative terminal of the FBT-4. Specifications The Monitor is powered by the fieldbus and draws 12-15 mA of current, depending on bus voltage and ambient temperature. The Monitor may be used in hazardous areas. Operating temperature range: 0-50ºC Weight: 300g Size: 11.8 × 5.0 × 2.1 cm Sect 4c-11 accurate characterization of fieldbus wiring FBT-5 fieldbus wiring validator The Fieldbus Wiring Validator, FBT-5, is used in combination with the Relcom Fieldbus Monitor, FBT-3, to test new or existing field wiring to determine its suitability for use in a FOUNDATION™ Fieldbus network. The FBT-5 acts as a signal generator, supplying DC power and a simulated fieldbus signal to the wire pair being tested. The FBT-3 is then used to take power, signal, and noise measurements. Testing can be performed on existing instrumentation wiring, multi-pair cables, newly installed fieldbus cable, or a complete fieldbus wiring system with wiring blocks and terminators already installed. Connection Using the clip leads, connect the FBT-5 to one end of the cable. To the other end, attach the Test Terminator. Connect the FBT-3 to the Test Terminator. Be sure to attach the red clips to the positive fieldbus wires and the black clips to the negative. If the wires are reversed, the Monitor will not function. FBT-5 T Cable to be tested FBT-3 Operation The Wiring Validator has a push-button Power switch to turn it on or off. If the Wiring Validator is turned on with a single click of the Power button, it will stay on for about 5 minutes and then automatically turn itself off to conserve battery power. If the Wiring Validator needs to be powered on indefinitely, such as when wire testing is being performed by a single person, press and hold the Power button for about 3 Sect 4c-12 seconds. The green Power On light shows that the Wiring Validator is on. • If the Power On light blinks rapidly (about three times per second), the Wiring Validator or Fieldbus Monitor is not attached to the wire pair or the connection is reversed. • If the Power On blinks slowly (about once a second), there is a good connection to the wire pair and Fieldbus Monitor, and the Wiring Validator is in battery save mode (and will automatically power down in about five minutes). • If the Power On indicator lights continuously, all connections have been made properly and the Wiring Validator will stay on until it is manually powered off. When the Wiring Validator is turned on, the Fieldbus Monitor powers up and displays the following readings: • Voltage should be between 9 and 10 Volts • Push the Monitor's Mode button once to get the LAS function. The LAS signal level reading should say "OK" and show the signal level in millivolts: LAS Signal (mV) Wire Condition 350 or more Excellent 200-350 Good 150-200 Marginal 150 or less Not Good • Push the Monitor's Mode button three times to get the NOISE AVerage reading. It should say "OK" and display the average noise level: Noise Level (mV) Wire Condition 25 or less Excellent 25-50 Good 50-75 Marginal 75 or more Not Good Wire System Testing A complete fieldbus wire system, with two terminators and other wiring blocks installed, can be tested before field devices are connected. This is done in the same way as the wire testing described previously except that the Test Terminator is not used. Note: The wiring system cannot have fieldbus devices attached to it during testing. The Wiring Validator is not capable of providing power to the fieldbus devices and its signal generator will interfere with any data transmission that the fieldbus devices attempt to initiate. If the wiring system has two terminators installed (as required for proper fieldbus operation), test results will be comparable to the results of the wire by itself. However, if too few or too many terminators have been installed, the measured signal levels will be inaccurate. The chart below shows the relative values of LAS signal level that will be observed: Terminators LAS Signal (mV) 0 999 1 961 2 (correct number) 760 3 637 Error Conditions A blinking Low Battery light indicates that the outputs of the Wiring Validator are shorted. The Low Battery light may also flash briefly as the Wiring Validator is first attached to a wire pair. A continuously lit Low Battery light indicates that the batteries need to be replaced. Self Test To verify that the Wiring Validator and the Fieldbus Monitor are working correctly, connect them to each other through the Test Terminator. Observe the power, signal, and noise values and verify that they are within the following ranges: Measurement Acceptable Range Power 9 to 10 Volts LAS Signal 700 to 800 mV Noise AVerage less than 25 mV If the observed values fall outside of these ranges, replace the batteries as described below. If the problem persists, contact Relcom for assistance. The unit contains no user serviceable parts. Additional Wiring Tests To get a complete characterization of the fieldbus wiring, measure the resistance between the individual conductors in the cable using a standard ohmmeter. Suggested measurements include: • The resistance between the twisted-pair wires • The resistance between each of the twisted pair wires and the shield/drain (if present) • The resistance between the shield/drain and instrument ground bar. Readings of 100K ohms or higher are acceptable. Additional System Requirements A Relcom Fieldbus Monitor, FBT-3, is required to obtain signal and noise measurements as described in these instructions. 1.22" 31 mm Fieldbus Wiring Validator Power On Low Battery FBT-5 5.08" 129 mm Power 2.75" 69.9 mm ORDERING INFORMATION Description Fieldbus Wiring Validator Fieldbus Monitor Part Number FBT-5 FBT-3 Batteries The Wiring Validator uses four replaceable AA alkaline batteries. Under continuous use, the Wiring Validator's batteries last about 12 hours. To replace the batteries, remove the four screws on the back of the Wiring Validator to release the cover. Specifications The FBT-5 includes batteries, soft case, Test Terminator, clip leads, and operating instructions. Operating temperature range: 0 to 50°C Dimensions: 12.9 × 7.0 × 3.1 cm (5.1 × 2.8 × 1.2”) Weight: 600 g Caution The Wiring Validator must not be used in hazardous areas or to power wiring that runs into hazardous areas. Sect 4c-13 NOTES Sect 4c-14