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SOLO Alarm-relay set from Modbus

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  • SOLO Alarm-relay set from Modbus

    Hi, Im using a SOLO 4896 with 0-10v control output connected to D0-06DR via Modbus RTU. I was wondering if it would be possible to control the alarm-relays by modbus bits. I would like to use the relays as external outputs from the PLC.

    Regards, Gudmundur


  • #2
    you can connect to the SOLO via the serial port (RS-485)... I have a few tied into a DL260 doing this now. I read all status & write temp set points and hi/low alarm values.

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    • #3
      Yes I know and that is working fine. What I was trying to ask, is if I can toggle the alarm relays in the SOLO from the PLC. I would for example to start a pump when I start the SOLO controller. I would then like to be able to use the Alarm (out2) relay to start the pump from the PLC.

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      • #4
        page 2, chapter 7 of the SOLO manual (Modbus Communication) shows most bits to be R/W, so you should be able to toggle them

        http://www.automationdirect.com/stat...ntrolm/ch7.pdf

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        • #5
          Originally posted by Gudmundur Ben View Post
          Hi, Im using a SOLO 4896 with 0-10v control output connected to D0-06DR via Modbus RTU. I was wondering if it would be possible to control the alarm-relays by modbus bits. I would like to use the relays as external outputs from the PLC.

          Regards, Gudmundur
          I suppose one could, sort of. I don't see bits for any of the alarm outputs per se (though there are read only bits for the alarm indicator LEDs). However, if one really wanted to, one could set the alarm set point to a value that would always be "on" e.g. a "high limit" below freezing for a boiler application, or low limit above boiling for a refrigeration application, Then enable or disable the alarm via MODBUS (P3-8 - P3-10)

          One thing to keep in mind, as far as I know the Solo writes to its flash any time a parameter is changed and flash memory does have a finite write endurance.

          If you want a cheap remote output you might consider a CLCIK PLC

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          • #6
            Originally posted by Tinker View Post
            I suppose one could, sort of. I don't see bits for any of the alarm outputs per se (though there are read only bits for the alarm indicator LEDs). However, if one really wanted to, one could set the alarm set point to a value that would always be "on" e.g. a "high limit" below freezing for a boiler application, or low limit above boiling for a refrigeration application, Then enable or disable the alarm via MODBUS (P3-8 - P3-10)

            One thing to keep in mind, as far as I know the Solo writes to its flash any time a parameter is changed and flash memory does have a finite write endurance.

            If you want a cheap remote output you might consider a CLCIK PLC
            Thanks Tinker, I had already implemented your method. I think that is the easiest and cheapest solution.

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