adccommunitymod (AutomationDirect) asked a question.

Signet pH/flow probes and S3L

Created Date: October 24,2016

Created By: Frontier

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Has anyone figured out how to talk to Signet S3L sensors over RS232? According to their manuals, it's a serial ASCII format, so I'd imagine a PLC would be able to communicate if it had the right strings to request data...


  • adccommunitymod (AutomationDirect)

    Created Date: October 24,2016

    Created by: Frontier

    Has anyone figured out how to talk to Signet S3L sensors over RS232? According to their manuals, it's a serial ASCII format, so I'd imagine a PLC would be able to communicate if it had the right strings to request data...

  • adccommunitymod (AutomationDirect)

    Created Date: October 25,2016

    Created by: plcnut

    I have not tried to talk to anything from Signet.

    The Do-more has successfully talked to all the ASCII devices that I have tried so far.

  • adccommunitymod (AutomationDirect)

    Created Date: October 26,2016

    Created by: Frontier

    Yeah, I definitely wasn't concerned about any limitation of the Do-More, of course! Just interested in hearing from people out there.

  • adccommunitymod (AutomationDirect)

    Created Date: April 07,2017

    Created by: dd33

    Sorry to revive an old thread but did you ever make any progress communicating with the Signet devices via S3L?

  • adccommunitymod (AutomationDirect)

    Created Date: April 12,2017

    Created by: Frontier

    I hadn't had the time, but I'm planning on working on it tonight. I'll post my results.

  • adccommunitymod (AutomationDirect)

    Created Date: April 16,2017

    Created by: Frontier

    ...and I'm the worst. I worked so late I completely forgot about it. I'm going to start this now.

  • adccommunitymod (AutomationDirect)

    Created Date: April 19,2017

    Created by: Frontier

    Okay, a few days late, but here's what I found:

    The S3L protocol is TTL-level single-wire bus. The sensors are powered by 5VDC, and the data line is referenced to ground. It communicates at 9600 bps, with 7 data bits, no parity, 1 stop bit, and no flow control.

    I'm able to snoop on the traffic between a Signet display using an Arduino as a TTL converter. I 've identified a few things about the data stream, and can reliably pull data from it into a Do-More simulator (even scaling to an analog output), but any attempt to talk back to the sensor fails. Additionally, the sensor doesn't send any data without a request from the display (which I don't seem able to replicate).

    I'm too far in to stop now. I'll keep you posted.

    Expand Post
  • adccommunitymod (AutomationDirect)

    Created Date: May 10,2017

    Created by: Frontier

    Sorry everyone. I got bogged down with a bunch of projects. I'll get back to working on this in a couple of weeks.

  • adccommunitymod (AutomationDirect)

    Created Date: February 23,2020

    Created by: mencomputer

    ayuda protocolo s3l de signet

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