RS422 testing?

[Dave Clark]

I have an RS422 serial data interface with a DB25 connection to my
PC computer com port that I would like to test. The other end of the RS422
connects to a microscope with powered X Y Z axis through a DB15 connector
on the scope, but I am not convinced that the microscope is getting any data
from the RS422.
Supposedly, a simple space character sent through the terminal
program in windows is suppose to initiate a position response for X Y and Z
from the microscope, but there is no response. I have noticed that the space
character results in a potential pulse on pin 2 of the DB25 com port, what
should I be seeing on the other end of the RS422 when it is connected to the
com port?

The pin-out on the DB15 end is:

1- FR. GND SHLD
8- SIG. GND
9- RD(B)
10- RD(A)
11- TD(A)
14- TD(B)
15- +12V
rest open

I suspect I should be looking for some type of output at TD(A) or TD(B)
when I send a space in the terminal program. I didn't find anything with my
oscilloscope at these pins, but I didn't really know what I was looking for.
There is no doubt a better way to test this thing - any ideas? Thanks

--
Dave Clark
Georgia Institute of Technology, Atlanta Georgia, 30332
Email: gt6...@prism.gatech.edu

[Chris Mann]

Are you sure that the computers serial port is configured for RS422 and not
RS232 (standard PC com port)? Are you using the right cable? If so then you
may need a break-out box.

Dave Clark wrote in message <7uo9sg$3...@catapult.gatech.edu>...

[Dave Clark]

Chris Mann <chri...@sprintmail.com> wrote:
: Are you sure that the computers serial port is configured for RS422 and not

: RS232 (standard PC com port)? Are you using the right cable? If so then you
: may need a break-out box.

Sorry for the confusion, I mean to say that I have an RS422
_converter_ connected to my computer. It is the converter that I am
unsure about and would like to test.