Re: Ethernet to RS-232 Danfysik supply connection issues

[Mark Rivers via Tech-talk <tech-talk@aps.anl.gov>]

 >  Talking directly to  the power supply via an old machine with a serial port also gets no response from the supply.

Here are things to do when trying to get RS-232 to work.

- If you have the manual for the power supply read its description of the RS-232 communication.  It should document how many data bits and stop bits, parity, baud rate, etc.

- Check that the device and the computer/Moxa are not transmitting on the same pin (2 or 3).  Disconnect the cable and measure the voltage from pin 2 to ground and pin 3 to ground on both the device end and the computer/Moxa end.  You will find that either pin 2 or pin 3 is at least -5V while the other is floating. If they both have -5V on the same pin then you need a "null modem" cable that swaps pins 2 and 3.

- The device may be using hardware flow control, and so requires some other pins to be asserted before it will reply.  You may need to enable hardware flow control on the computer/Moxa.

- Make a breakout cable so you can display both pins 2 and 3 on an oscilloscope when you are trying to communicate.  You should see the characters being sent from the computer/Moxa as square waves on one pin and any response from the device on the other pin.  If you see any response from the device then you probably have a problem with parity, stop bits, baud rate, etc.

Mark

________________________________
From: Tech-talk <tech-talk-bounces@aps.anl.gov> on behalf of Marissa Kranz via Tech-talk <tech-talk@aps.anl.gov>
Sent: Monday, December 23, 2019 6:29 PM
To: tech-talk@aps.anl.gov
Subject: Ethernet to RS-232 Danfysik supply connection issues

Hello,

I am trying to establish remote control of a Danfysik system 9700 magnet
power supply via a Moxa ethernet to RS-232 adapter (NPort 5150). We can
talk to the Moxa adapter just fine and confirm that message sent from
EPICS or a terminal successfully reach the adapter, but the supply never
responds nor sends any error messages or anything. Talking directly to
the power supply via an old machine with a serial port also gets no
response from the supply.

Has anyone ever used the Danfysik system 9700 and have any wisdom they
could offer?

Thank you,
Marissa Kranz

--
Marissa Kranz
Research Engineer
UW Medical Cyclotron Facility
University of Washington School of Medicine
425.246.4964