Test Points - Communication Terminals; Figure 56 - Control Board Communication Test Points; Table 17 - Communication Voltage Test Points - Keyscan CA250B Technical Instructions

Test Points – Communication Terminals
The following table outlines the correct voltages for the test points on the communication terminal on the CA
or EC control board.
Communication Test Point
CA / EC Communication Terminal
RS-232 connected to ACU
GND
TD
RD
DCD
DTR
CTS
Keyscan Inc. – Technical Guide (PC109x - 04.15)
Table 17 – Communication Voltage Test Points
Voltage
(-) 9 VDC
(-) 10 VDC
n/a
n/a
Figure 56 – Control Board Communication Test Points
Control Board
(PC 109x)
KI-00194E-07-11
Instructions/Notes
Connect voltmeter COM to GND on ACU communication
terminal block or green on data cable.
TD is an ACU generated voltage
RD is a PC generated voltage
CTS
DTR
DCD
RD
TD
GND
RS-232 (COM4)
IOCB (COM1)
RX
TX
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