Re: [DIYbio] RS232 / GSIOC Command line troubleshooting for a Gilson HPLC Prep

So when I suggested "like two machines trying to talk to the same device at once", I was close.

:-)

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On Wed, Apr 8, 2020 at 7:36 AM Dakota Hamill <dkotes@gmail.com> wrote:

For histories sake, it appears that both the master and slave units thought they had the same ID and were communicating on the same channel.  By sending a buffered %331 %332 command to each, was able to assign them their separate ID's of 1 and 2 respectively, and now we have solvent flowing!   

Thanks for the discussion. 

On Tue, Apr 7, 2020 at 7:42 PM Dakota Hamill <dkotes@gmail.com> wrote:

Very helpful thank you, never knew there could be so much to it.  

Tomorrow I'll try to connect 1 pump at a time, and remove them from their series to the controller unit.  They are all on the same surge protector, which shares a 2 plug box with a small bench-top Tuttnauer autoclave that was heat cycling throughout the time period I was trouble shooting.  The scans through the 1-63 channels would sometimes show the gibberish for ID 1 (pumps), and sometimes would not.  There seemed to be no pattern to what would cause the pumps to show up or not, so perhaps it was the autoclave heating intermittently. 

The gibberish did change each time, but some of the symbols seemed constant, like the F. 

Appreciate the response, kind of fun to trouble shoot things.  Will start with a different power outlet and report back tomorrow. 

On Tue, Apr 7, 2020 at 7:18 PM Simon Quellen Field <sfield@scitoys.com> wrote:

If the gibberish is different each time, and you are sure that the device is trying to send the same data each time, you don't have a baud rate issue.

If sometimes you get what looks like a valid error number, that rules out problems like level shifting (e.g. using TTL levels instead of RS232).

You might want to check voltage levels or see if there could be something introducing noise (like two machines trying to talk to the same device at once).

A weak power supply could cause noise in the line, especially if a current-hungry motor or heater was getting turned on or off as the message was sent.

If one device is sending Unicode to a device that expects ASCII, that could be a problem, but you said the garbage is different each time.

If one device is sending data faster than the receiving device can take it, you can get garbage. The sender may be expecting hardware flow control and your cable doesn't have those wires connected.

Use a full cable, or switch to software flow control.

Some devices send boot messages at one baud rate and then switch baud rates to communicate. But again, the garbage would be the same each time.

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On Tue, Apr 7, 2020 at 2:42 PM Dakota Hamill <dkotes@gmail.com> wrote:

Hello all.   Asking for some troubleshooting help, DIY Analytical chemistry, close enough for DIYBio as I'm at my wits end messing with cables and baud rates.

Stringing together an HPLC system and could type out a story or attach my sweet MS Paint diagram of how things are connected, but the real question is, what would cause a machine to respond with gibberish characters when asked it's name in a command line as seen in the picture below?

GSIOC may be Gilson's own serial communication setup, and I know next to nothing about coding etc.

However when I ping the liquid handler or the UV/Vis machine with a "%" command, it returns the modules name and software version number, when I ping the HPLC Pumps with the same command, it returns a different array of gibberish characters each time, or an #error.

I've set baud rates on everything to 19200 which it's defaulted to, or Externally set on the HPLC pumps, no difference.

Perhaps a long shot but didn't know if people that new older serial port machines knew if random giberish was coming up, it's just a bad baud rate somewhere along the line, or something might be out of order.

Thanks! -Dakota 

https://imgur.com/a/fJsCsur

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