WattMaster WCC III part 10 - Manual (Page 23)

10. RS-485 COMMUNICATIONS
WCC III Technical Guide 10-21
Global Bridge Troubleshooting with a Digital Voltmeter
Figure 10-31: Typical Global Bridge RS-485 TUC Communications DC Voltage Measurements with the SAT
COMM Loop Connected
Figure 10-32: Typical Global Bridge RS-485 TUC Communications DC Voltage Measurements with the SAT
COMM Loop Disconnected
Global Bridge Communications Troubleshooting with a Digital Voltmeter
The voltage measurements in Figure 10-31 are approximate voltages. These voltage measurements are taken when the power to the
Global Bridge Controller is “ON” and the RS-485 SAT III communications loop is connected. These two voltages will fl uctuate slightly
and also will momentary “fl ip” to the other meter reading’s value. The voltage measurement from “T” to “SHIELD” should be around 2.7
VDC. The voltage measurement from “R” to “SHIELD” should be around 3.00 VDC. Typical bad voltage measurement values would be
anything above 3.8 VDC and anything below 1.5 VDC.
The voltage measurements in Figure 10-32 are approximate voltages. These voltage measurements are taken when the power to the
Global Bridge Controller is “ON” and the RS-485 SAT III communications loop is disconnected. These two voltages will not fl uctuate.
The voltage measurement from “T” to “SHIELD” should be around 3.25 VDC. The voltage measurement from “R” to “SHIELD” should
be around 3.25 VDC. Typical bad voltage measurement values would be anything above 3.8 VDC and anything below 1.5 VDC.