Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 276)

276 Publication 1753-UM001C-EN-P - March 2010
Chapter 22 Communicate with Modbus and Profibus Devices
Connect the Controller to a Modbus Device
Configure the Modbus Serial Port
You must either create a new project or open an existing project
before you can configure Modbus communication. Once the software
opens a project, it automatically displays the Hardware Management
window, from which you configure the Modbus port.
1. Right-click Protocols and choose New>Modbus Slave.
L- L+ L+
COMM3
ASCII
RS-485
24V DC
COMM2 COMM1
GuardPLC Ethernet
10/100 BaseT
MODBUS
3 (—) 4 (—)
3 (—) 4 (—)
RS-485
Connection Signal Function
1 --- ---
2 RP 5V, decoupled with diodes
3 RxD/TxD-A Receive/Transmit data A
4 CNTR-A Control Signal A
5 DGND Data reference potential
6 VP 5V, positive pole of supply voltage
7 --- ---
8 RxD/TxD-B Receive/Transmit data B
9 CNTR-B Control Signal B
IMPORTANT
The Modbus port is RS-485. You must use an electrical
interface device to connect the controller to an RS-232 device.