Serial Data

I need to receive serial data from an AB FlexLogix 5433. I have a
test program on the PLC that does nothing but send Ascii data with an AWA instruction. This is a test case, since I need to write an
application running on a PC that will receive data from the PLC
serial port. I have built a cable according to the AB specs for
an Ascii device, and I am reasonalby sure the serial port on the
PLC side is configured as it needs to be. On the PC side, I am
using COM1, which uses the XP serial driver. I want to be able to
look at the characters with a terminal emulator, like hyperterminal.
I have not been able to do this. There is data comming out the PLC
verified via a scope. Does anyone know why I cannot get
the terminal emulator to display the data ? I am going to try a
serial monitor next. Does anyone know what the cable should look like ? I thought I would try a three wire cable (pins 2,3 and 7) then
try a null modem cable.

You didn't mention anything about you data setup. Baud rates, Bits, Parity, etc. Make sure that what the PLC is sending and what the PC is looking for match.

I do this sort of thing all the time, and if I have trouble is's 10% the framing (parity, data bits, stop bits, speed) and 90% of the time it's my home-made cables and connectors.

All Logix controllers have a DTE-type serial port, same as your PC does. For this reason, you need a "null modem" cable.

For ordinary ASCII, all you need is three wires:

2 - 3
3 - 2
5 - 5

cable

You indicate that you have used pin 7.
Pin 7 is a GND on a 25 pin DB connector. It's 5 on the DB9
connector. If you are using the PC equipped with DB9 you need to
use pin 5 not 7.

Good eye, Jiri ! I totally overlooked that.