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PC ↔ 422/485 SERIAL INTERFACE
4.1 Self-Testing
The PC
422/485 Serial Interface can perform a self-test to check for
↔
hardware and setup problems. To run this test, follow the steps below:
1.Install jumpers on the data pins of the card's DB25 connector, as shown
in Figure 4-1 below.
2.If the card is using the port address COM1: or COM2:, get a copy of a
communication-software package such as Crosstalk
ProComm
®
PC. (If you've set the card to use one of its nonstandard addresses—see
and
Step 1
necessary.)
When performing a self-test, make sure the driver on the card is always
enabled (E2 removed). Also, be sure the driver is not controlled by RTS
during the test.
3.Configure the software to use full duplex and to match the card's port
address.
4.Run the software in its terminal mode.
5.Type some random characters on the PC's keyboard.
14
4. Troubleshooting
PC-422/485 CARD
Figure 4-1. Self-test setup.
that can emulate a dumb terminal. Install it on the card's
in
Figure 3-1
Chapter 3
TX+ 24
TX- 25
RX- 13
RX+ 12
—special software will again be
NOTE
, SmarTerm
, or
®
®
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