Hardware diagnostics on serial port

[Paula J Frazer-Campbell]

Hi to all,

I am looking to elimate the serial ports (Mux) from problems I am having with some encription boxes (TCL280) and want to fully check out the serial ports.

How can I verify that the mux card and serial ports are behaving correctly?

Paula

[Helen French]

Hi Paula:

I would try some of this:

1) Connect a serial printer in the ports and redirect a file to it.
2) Connect a modem and check the connectivity.
3) Connect a terminal to the ports and enable the getty process in /etc/inittab file. Check whether I get a login screen

HTH,
Shiju

[Paula J Frazer-Campbell]

Hi

I am looking along the lines of a loopback test as well.

Paula

[Rodney Hills]

If you have access to a break-out box, you could use it to make sure the right pin outs are hot.

Primary pins are 2 (xmt), 3 (rcv), and 7 (gnd). Many devices are dependent on pin 20 (dtr). Some devices use 4 & 5 for hardware handshaking (cts/rts).

Hope this helps.

-- Rod Hills

[Paula J Frazer-Campbell]

Hi Rodney

I have a breakout and know the loopback, but how to fully test the port from the server?

Paula

[Mark Greene_1]

>>I have a breakout and know the loopback, but how to fully test the port from the server? <<

Get a modem and plug the break-out box into the mux and then into the modem, so the box is in the middle of the link. Then you can cu from the command line to the modem and see what lights on the box when doing so. You can then do this for each port on the mux.

HTH
mark

[Bill Hassell · Accepted solution]

Most likely the problems you are having are reelated to the default behavior of all serial ports on HP-UX. To start with, they are always sitting at 300 baud (not 9600 baud). To change this, you must decide: is the port going to be used directly by a program, or is it going to be used for printing or is it to be used for interactive login?

1. Directly by a program: the program must explicitly open the port and set the communication parameters. There is no easy way to keep the port from being reset to 300 baud after the program exits.

2. For printers: the printer model scripts all have serial initialization commands--be sure that they are active in the script.

3. For terminals, setup gettydefs. Note that gettydefs has had obsolete settings for more than 10 years. Setup a gettdefs entry for direct-connect terminals similar to the console entry (CS8 is the important setting along with 9600 baud).

If the port(s) can login with an ordinary terminal, they are fine and you will have verified bi-directional communication. Foreign equipment likely has a problem because optional signals such as DTR, DCD and others are not asserted in the manner required by the foreign equipment. You'll need a breakout box and some jumpers (plus a manual) to verify all this.