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Servo Valve Control

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  • Servo Valve Control

    I am wanting to write a program to control a setworks application on a sawmill carriage. Currently it has a tempsonic transducer it uses for position feedback, and a simple on/off hydraulic valve to control the movement of the head blocks. The system works great but we are getting some missed sets, and the system is rather slow for what we are wanting to do now.I believe that the set works can be dramatically improved with a servo valve setup. I have more than 9 moog servojet valves on hand. I believe they are a 10-32vdc supply, and a 0-10vdc signal. I believe they have built in electronics. Can this valve be controlled by a plc with analog, and possibly a high speed counter, or coprocessor. Do I need a servo amp? and if so does AD have a product capable of this or can the direct logic plcs easily be interfaced with another brand amp.. We currently have another saw running a DL-06 i believe with an analog card and a coprocessor that drives a servo valve, and it works great.
    I haven't had the opportunity to write a program for a servo valve system before so Im new to them. Any input would be greatly appreciated

  • #2
    you should be able to control those servojet valves with an analog voltage output module

    for the tempsonic transducer, is it TTL, or analog out?

    if you get a decent list of the devices & capabilities, putting together a plc to control it will be easier.


    • #3
      I left the specs on the transducers I have at work. I believe they are a 9-32Vdc supply, and it uses a pulse width output.. the transducer part of the system can vary. I can go with an analog if necessary. The saw we currently have running has a D0-06DR-D plc with a FO-CP128 co processor, FO-2AD2DA-2 Voltage analog output card, a dc input card , and a dc output card. I am wanting to try to get away with running the same plc and cards if possible, so that I can keep spares that will work with either machine. The only part difference will be the length of the transducers, one will be twice as long as the other. I believe the servo valve is being run by the FO-CP128 co processor. Does this sound like the proper system to run for the new machine also? or is it recommended to go up to a 305/405 and a drive for the valve?


      • #4
        I have figured out that what Im calling an amp Isnt really the part that Im inquiring about. What Im looking for is a motion controller for the servo valve. Im pretty positive I can get the control I want from the PLC, but IM looking at miles and miles of code. I do think a controller is the best way to go. Has anyone else integrated a Koyo plc with another brand such as MOOG, Parker, Continental Hydraulics, or others. IM needing to control accel, decel, position etc.IM pretty sure automation direct doesnt offer a product to do this type of control, or Im looking in the wrong places. I know I can make it work but im looking for something to make the programming go a little faster. Any input? I would really like to avoid any of the $1500 and up controllers from these other companies?


        • #5
          look into the Do-More for your PLC... this will greatly simplify the coding.

          For that valve, does it take ASCII? Is that the reason for the CP128? IF so, it's easily replaced with a SERIO module.

          again, it really depends on your devices...


          • #6
            9 out of 10 sawmills use a Delta Motion Systems RMC to do exactly what you are doing. They are very reliable, very accurate, and unfortunately, way over your budget.

            I know this information doesn't help you, but I just wanted to make sure you knew that.

            The RMC doesn't take the place of the plc though either.


            • #7
              The reason for the cp128 was simply do to the fact that I have another machine that uses it to control a prop valve. I found a few controllers that I believe accept ASCII, but I dont think they will suit my needs if I expand the system in the future. As for cost Im very aware of what the prices of the equipment that Im looking for are. None of it is cheap. I priced a New MOOG servojet valve today and quit breathing. Makes me happy that I have 6 brand new ones. I would love to run the delta or MOOG stuff but Im simply trying to keep as much of our equipment, and electronics the same as possible. It cuts down on our spare parts inventory and cost, and just makes my job a lot easier. But with how most things go I will probably end up with one of the 2 anyway.. Im not sure what the current system cost is , but the system it replaced was somewhere around $200,000.00 several years ago. Well 20 years ago. Makes you sick that some of it is out dated and not usable.