rs232 question

[malua mada!]

I have a controller that talks rs232 ,driven by a MAX232.
3 wires only.
I connect the computer to it: works fine.
I am connecting a StarTech NETRS2321E Net adapter to it. Won't work.
Loopback plug instead of controller: works fine.
Since the harness on the controller side includes a DB9 tap I decided
to hook the computer into that, and LO! that causes it to work!
I get communication on both channels , one from serial port, one from
NETRS232.
If I unplug the serial port cable at the controller the NETRS232
quits receiving data.
If I unplug the serial port cable at the computer the NETRS232
continues receiving data.
What is going on? What changes to the controller circuitry would help?
Cheers
f

 

[Jamie]

malua mada! wrote:

I have a controller that talks rs232 ,driven by a MAX232.
3 wires only.
I connect the computer to it: works fine.
I am connecting a StarTech NETRS2321E Net adapter to it. Won't work.
Loopback plug instead of controller: works fine.
Since the harness on the controller side includes a DB9 tap I decided
to hook the computer into that, and LO! that causes it to work!
I get communication on both channels , one from serial port, one from
NETRS232.
If I unplug the serial port cable at the controller the NETRS232
quits receiving data.
If I unplug the serial port cable at the computer the NETRS232
continues receiving data.
What is going on? What changes to the controller circuitry would help?
Cheers
f

Maybe you're not using the correct on COMMON on the plug?

--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

SOME PEOPLE ARE LIKE SLINKIES. NOT REALLY GOOD FOR ANYTHING BUT
THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.
http://webpages.charter.net/jamie_5"

 

[malua mada!]

On Apr 1, 6:31 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

malua mada! wrote:
I have a controller that talks rs232 ,driven by a MAX232.
3 wires only.
I connect the computer to it: works fine.
I am connecting a StarTech NETRS2321E Net adapter to it. Won't work.
Loopback plug instead of controller: works fine.
Since the harness on the controller side includes a DB9 tap I decided
to hook the computer into that, and LO! that causes it to work!
I get communication on both channels , one from serial port, one from
NETRS232.
If I unplug the serial port cable  at the controller the NETRS232
quits receiving data.
If I unplug the serial port cable  at the computer  the NETRS232
continues  receiving data.
What is going on? What changes to the controller circuitry would help?
Cheers
f

Maybe you're not using the correct on COMMON on the plug?

Well now it works by itself.

I'll see if it has to do with temperature after I shut it off tonight.