HC900 Hybrid Controller Installation and User Guide

Communications Installation - Connecting the HC900 Controller to Modbus device(s)
Revision 5 HC900 Hybrid Controller Installation and User Guide 105
9/03
Connecting the HC900 Controller to Modbus device(s)
RS-485 Modbus connections
Using the master and slave(s) RS-485 ports of the controller and other device(s), connect as shown.
Master
120 ohm
Slave 1
Slave 2
Slave n
. . .
120 ohm
TX/RX-
TX/RX+
TX/RX-
TX/RX+
TX/RX-
TX/RX+
Shield
Shield
. . .
. . .
. . .
120 ohm termination resistors required at master and last slave on the link.
TX/RX-
TX/RX+
Use HC Designer software to configure the controller’s RS-485 port as a master or slave.
RS-232 Modbus Connections
Connect to the RX, TX, and ground pins of the controller’s 9-pin RS-232 port. Table 17 (page 90)
identifies the pins. For connections on other device, refer to its product manual.
For multiple devices on RS-232, use an approved RS232-to-RS485 converter.
Use HC Designer software to configure the controller’s RS-232 port as a master or slave.