Posted by Paul G on April 26, 19101 at 07:20:53:
In Reply to: rs-232 loopback pinout posted by vince on April 25, 19101 at 14:14:36:
Ok, i checked the voltage on the "broken" COM2.
1 & 5 = 9.5 volts
2 & 5 = 10
3 & 5 = 10
4 & 5 = 8
6 & 5 = 7
7 & 5 = 10.5
8 & 5 = 10
9 & 5 = 5.5
: Ok, here's the pins to connect together to make a loopback mode. After this is done, try running hyper terminal (not the best way, but it works) and set up to work direct from that com port. You should be able to type and what you type should show on screen. If not, either check connection or this verifies blown com port. By the way, this also works for any rs-232 com program on any rs-232 machine!
: connect pins 1 and 7 and 8 together
: connect pins 2 and 3 together
: connect pins 4 and 6 and 9
: This is for the DB-9 connector as viewed here:
: \1 2 3 4 5/
: \6 7 8 9/
: A good way to make the jumpers is a device called a break-out-box. it has 2 25-pin connectors and lights and switches with jumper wire connectors to make this a snap. I've used one in the field to make null-modem cables out of standard cables for testing.
: Voltage testing, well, pin 5 is ground, test that first, if any of the other pins carries a voltage with the pc off thats a problem. NO voltage should be in the cable with power off. I'm at a loss also as to why if both machines were off how the port blew, but I have seen many blow while power was still on. Let me know if this helps
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