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AC7A/B User’s Guide
TWO-WIRE RS-485 MODE
A few minor modifications must be made if you are using the AC7A/B in 2-wire mode.
First, you will probably have to make your own custom RS-232 cable from the AC7A/B to the PC. This is to ensure
that DTR (pin 20) on the AC7A/B’s RS-232 connector is not connected. If you are using a 25-pin port on the PC,
then you’ll need to make these three connections:
Figure 4-1: 25-Pin RS-232 Cable for AC7A/B RS-485 2-Wire Mode
If you are using a 9-pin serial port on the PC, then you will need to wire these connections:
Figure 4-2: 9-Pin RS-232 Cable for AC7A/B RS-485 2-Wire Mode
ADDITIONAL TECHNICAL INFORMATION
