ProTechTPS Total Protection System
Manual 26710V1
48
Woodward
If DI wetting voltage is from an external supply, it must be an
isolated, power supply. The module input power source of 24 Vdc
may not be used. Tying the input power to the Discrete power causes
bias offsets which make the supplies susceptible to transients. The
supply must also be referenced correctly to Discrete PWR by
connecting the two commons.
Figure 2-17. Power Supply Relationship Diagram
Serial Modbus Communications
One serial communications port per module (A, B, C) is available for Modbus
communications to a plant DCS (distributed control system) or local HMI (human
machine interface). This serial port can be wired and configured for RS-232 or
RS-485 communications, depending on the specific application requirements.
Refer to Figure 2-18a for RS-232 wiring information, and Figure 2-18b for
RS-485 wiring information.
Figure 2-18a. Serial Port Interface Diagram—RS-232
20
19
18
17
16
15
14
13
RXD
TXD
COM
ProTechTPS
Module
ISOLATED
RS485 / RS232
PORT
+5V
S_GND
Modbus
Master
Device
RXD
TXD
COM