Model 5100-28-IT Combustible Gas Sensor Module
1.4.2 MODBUS OPERATION
An RS-485 Modbus RTU serial interface allows direct connection to standard PLCs and DCSs. The
Module Address Switch (section 4.5) allows the user to select up to 15 different Modbus addresses. Also,
up to 254 different Modbus Addresses are available via menu selection. Figure 4-5 in this manual provides
the wiring terminations for Modbus connections.
1.4.3 ANALOG OPERATION
The analog 4-20 mA interface allows direct connection to standard controller and distributed system. The
module is an active current source.
The standard configuration is set up for a 3-wire non-isolated connection. An optional 4-wire isolated
connection is also available and can be enabled by changing JP1 and JP2.
1.4.4 REMOTE SENSOR (APPENDIX E)
The Remote Sensor option, enables the remote mounting of the sensor up to 100’ from the transmitter.
1.4.5 HART CONNECTION (APPENDIX F)
A HART interface option is available. Refer to Appendix F for information.
1.4.6 OPTIONAL INTEGRAL RELAYS
The optional relays are integral to the gas sensor module and are rated as SPDT, 250VAC, 5 Amps for the
High Alarm and Low Alarm relays and SPDT, 250VAC, 0.25 Amp for the Trouble relay.
* HART option, alarm trouble relays are all SPDT, 250VAC, 2 Amp
If the gas sensor module is provided with the optional relays, it will include Terminal P4 on the interface
board (Figure 4-3). Relay output connections are on P4.
1.4.7 REMOTE ALARM RESET
An input is available for connection of remote alarm reset/acknowledge. Figure 4-6 provides the wiring
termination for connecting the remote alarm reset. This only resets local alarms, not Sentry alarms.
The sensor module of comprised of the following three primary components:
Standard on the 5100-28-IT is an explosion-proof, rain-tight cast aluminum electrical housing (Figure 1-2)
with three ¾” FNPT conduit hubs. The 5100-28-IT-SS has a 316 Stainless Steel enclosure (Figure 1-3).
Both enclosure covers have a viewing window. The design of the enclosure allows 3-way mounting choices
as shown in figure 1-1.
Electronic Assembly consisting of one printed circuit board assembly mounted under a cover plate,
plugged into one field termination board. Connectors for wiring for power, signal interface and alarm
relays are located on the bottom of the termination board.
The sensor assembly includes an explosion proof housing containing the gas sensor and a wiring harness
for connection to the transmitter. The sensor assembly threads into one hub of the enclosure. The
exposed end of the sensor assembly is threaded to allow connection of a rain-shield or calibration gas.