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SOLO SL4848 VR Possible to set ramp RATE?

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  • SOLO SL4848 VR Possible to set ramp RATE?

    Hey Guys,

    I feel like I may have bought the wrong PID controller. Trying to run a burnout oven here for jewelry casting which requires a very long ramp/soak sequence that requires me climb at say, 50C/Hr, then stay at Sv when i reach it. Then, climb again at so many degrees per hour. Etc etc. . The problem is, my PID here will go through the ramp soak sequence, but goes full blast from one value to another.

    Thats bad. That causes cracks in molds and possible molten metal everywhere.

    Is there something I'm missing? It works great as just a general temperature regulator.
    If not possible, I'm debating writting my own ramp rate software in something like AdvanceHMI and have it iterate through the ramps via modbus registers. or I may be forced to buy another controller.

    Any thoughts?

    Thanks in advance!

  • #2
    You have to use Ramp/Soak control. See section 12-10 of the quick start guide for the SL4848


    • #3
      while the SOLO ramp/soak programing is kind of a pain, I think it should be able to do what you want.

      "Then, climb again at so many degrees per hour."

      You will have to do some math for that, on the SOLO one sets the set point for a step and the time in the step. For example if you want to ramp from say, 20C to 300C at 50C/Hr. (and assuming you are at 20 when entering the step) you'd set the time at (300-20)/50= 5.6 or 5 hr 36 min.

      It's not entirely clear to me if you have actually fired your kiln with a ramp, or if just saw the displayed set point immediately jump up without displaying a ramp and assumed it wouldn't work (an assumption I also made before trying it on a real system).
      While the displayed set point does not show the ramp, a quick test I did seem to indicate that it is indeed ramping internally even if it is not showing you what it is doing.

      One thing to keep in mind if writing your own ramp function to use with the SOLO via Modbus is that as far as I know the SOLO writes to its non-volatile memory (I assume flash) each time a change is made and flash can only tolerate a finite number of writes, perhaps hundreds of thousands, but still, if writing is automated one might hit the limit eventually.
      My guess it that is why the thing won't display a ramping set point, if it was changing the set point in ROM, say, every few seconds, that could be hard on the flash, now why it can't display the value it has in RAM rather than ROM is another question

      If it really is not working for you (my test was rather simplified so I'm not 100% sure about the results) You might consider just buying a commercial kiln controller.

      Another thought, since you already own the SOLO, and there is no limitation on how often you read from it, on might consider using the SOLO just as a sensor interface and doing the control with something like a CLICK PLC, a C0-01DD1-D is only $100 and has a RS485 to talk to the SOLO, a RS232 for AdvanceHMI or a C-More micro or whatever. While the CLICK does not have a built in PID, it certainly has the math capability to do PID if you write one yourself
      Last edited by Tinker; 05-20-2019, 06:10 PM. Reason: Tried it in a real application on a real SOLO


      • #4
        Tinker , any update with progress? I bought a SOLO with the ramp soak feature and finally got it powered up. Was trying to determine how to program the program and came across this post.