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About mjrx

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  1. Devicenet to Mits VFD

    Yes, thanks for the reply. I got it sorted out, in the drive I needed to set the number of bytes I wanted to send to the devicenet card.  I was trying to read 8 points, but the drives default was 4 with instance 71/21.
  2. Devicenet to Mits VFD

    Trying to setup devicenet 1756-DNB to F800 mits drive. Have the eds file, everything seems to go ok but the module comes up in error 77 for that node. Is changing an eds file something that is normally done when setting these up? 
  3. Question on PowerFlex4 Drives

    Thanks. I didn't need to run loads, just needed to make sure the drives came to life. Just a temporary test on a panel that hasn't been used in some time, and it's offline in storage with only 240 single phase in house (I had a 480/240 transformer to convert to 480). Yes, I found they power up on single phase across L1 & L2. I have used Mits a lot and they work like this too. 
  4. Can anyone tell me if a 480V PowerFlex VFD will at least powerup on single phase 480V? I need to make sure the VFD's at least light up in a panel full of drives, there is no 3 phase available but I can feed them with a 120 - 480 single phase xformer, so L1 & L2 will have 480 to them. No loads are hooked up, so theres no danger of that. Just trying to see if the drives power up right now.
  5. 1784-PCMK driver

    Ok, thanks very much. I should have considered that.
  6. 1784-PCMK driver

    Anyone on where I can locate a driver for a 1784-PCMK series A card? Thanks.
  7. Very nice cbvance, thank you. That was the general direction I was heading, after some simulations I have run I have ruled out cascade control. I also was thinking about a single loop to control both with a seperate gain value to give more "weight" to the water over the air temp, kind of like making the vfd a slave follower to the water temp PID loop.
  8. Thanks for the help.
  9. I have been tasked with cooling a large motor. It has a VFD controlled cooling fan. There is an RTD at the intake area and another RTD after the airstream passes the motor. There is also a heat exchanger in the airstream that has chilled water passing through it. It also has an RTD at the water inlet and another RTD at the water outlet. The water flow through the exchanger is controlled by a modulating valve. My question is what type of control algorithm might be best for this arrangement? Should it be some type of cascade control, a single PID, differential, ??. It seems seperate PID loops may interact with each other and be hard to control. All 4 RTD's and analog to the VFD and valve are in place in my PLC and ready to go, I'm just not sure which way to go. Thanks in advance.
  10. I have RSLogix 500, FactoryTalk, and GX works 2
  11. Please don't read into my original post as a way to get around any licensing. I have paid hard earned $ for my licenses, and kept them up to date. So if I need to de-activate the license and then re-activate it on the new drive, so be it. I just wondered what, if anything, I will run into. Thanks very much.
  12. Now that the price of SSD's have come down so much, I have ordered a few to update some workhorse laptops that we use in the field. I then wondered if, when cloning the existing drive, would all of the licensing transfer over as well, specifically RS Logix. If the license is somehow linked to the drive's MAC ID, then I would think there may be an issue. Anybody run into any issues or have any tips on cloning a complete hard drive?
  13. RTD Wiring

    I have several 3 wire rtd's about 50 feet or so from my Plc input module. I was planning on using a high quality 3/c shielded cable for them. Is this acceptable wire, or is RTD wire necasary for this? Thanks.
  14. Its just an incremental quadrature 1024 ppr encoder, used for feedback between motor and drive. I found an encoder signal broadcaster that takes one encoder input and rebroadcasts it, optically isolated to up to four different devices. It is made by BEI. Thanks for the answers, I am now leaning more to a seperate encoder, and it will probably be a 16 bit absolute type.
  15. I have a motor feedback encoder going to back a servo drive. I need to also wire that same encoder to a PLC counter card to monitor position. There is not an encoder out on the servo to use for this, as some servos have. To complicate matters, I need this encoder to also go to a second redundant PLC. It cannot be switched between the PLC's as it needs to be live to both PLC's so the redundant PLC can keep track of position - in the case the redundant PLC gets called to action, it needs to know where (position) the other PLC left the machine. So in a nutshell I need one encoder to be paralleled across three devices. I know I just can't parallel them because of possible voltage level differences, loading issues, feedback problems, etc. Is there some COTS isolation device I can use for this, do I have to get creative with diodes, or other iso method I could try? Thanks in advance.