AERCO C-More Controls Manual June 2010 - Manual (Page 94)

C-More Controller for Benchmark, Innovation & KC
USER MANUAL
Page 94 of 162 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, New York 10913 04/22/14
GF-112 Phone: 800-526-0288 OMM-0032_0E
Note: The master does not need to be at an end of the daisy-chain loop.
Figure 8-3. Typical Daisy-Chain Modbus/RS485 Network
Any one of the C-More WHM units included in the Modbus network can be the Master.
However, it is recommended that you decide which unit will be the Master and which will be the
last unit on the daisy-chain prior to performing the wiring connections. This will simplify wiring
connections and Modbus address assignments.
Modbus network wiring connections must be made using shielded twisted-pair wiring, (18 – 24
AWG) such as Belden #9841, #3105A, #8760, or equivalent. The Modbus wiring connections
are made at the RS485 COMM terminals on the I/O board included with each C-more Control
System.
Connect the Modbus wiring as follows:
1. Starting at the first unit, connect the twisted, shielded pair cable to the RS485 Comm
plus (+) and minus (-) terminals on the left side I/O board as shown in Figure 8-4.
2. At the Modbus Master I/O board, activate the DIP switch labeled “MODBUS TERM” by
placing it in the up position. This will connect a termination resistor across the terminals
at the source end.
3. Refer to Figure 8-4 and run the shielded cable to the next unit in the daisy-chain and
connect the + and – wire leads (+ to +, - to -). DO NOT terminate the shield of the
RS485 Comm leads to the SHIELD terminal at the Slave. Instead, connect the shields
of the incoming and outgoing RS485 leads together.
4. Continue connecting the + and - wire leads and shields for the remaining units as
described in step 3 for the remaining Slave units in the chain.
5. At the end unit in the chain, activate the DIP switch labeled “MODBUS TERM” by
placing it in the up position. This will ensure that the termination resistors are activated
at both ends of the loop.
8.5.3 Control and Power Wiring
Control and power wiring connections to the sequencing valves associated with each C-More
WHM unit is accomplished by simply ensuring that the 3-pin Molex connectors on the units are
connected to the corresponding connectors on the valves