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  1. Constants value in PLC 5/20

    Yes you can change the value of a data table item by placing your cursor on the value in a statement as you have shown and just changing the value.  As Armadillo points out, you should do a cross reference of that value to make sure it is not overwritten somewhere else.  Keep in mind that it may be overwritten conditionally and may not immediately overwrite the value you put there but may do so when required by other logic. 
  2. Setting up Compact to work with Yaskawa VFD over Ethernet

    Yeah I'm not sure about that.  We have a custom AOI where I am using this so it would not be the same.  If you are using a Yaskawa AOI, then it should be documented in one of their manuals.  It should not care about the size of your drive or any about your motor characteristics.  That is all stuff that is configured in the drive.  You just care about start, stop, speed, faults, etc.
  3. Allen Bradley SLC 5/01 processor unit

    Not too familiar with the 5/01, but that sounds like you have lost the program.   Can you go online?
  4. Setting up Compact to work with Yaskawa VFD over Ethernet

    What AB PLC are you using and what Yaskawa drive?  Third party drives are actually pretty easy to setup on the logix platforms also - you just need to use a generic ethernet module.  All the settings in the module are in the Yaskawa Ethernet I/P manual if you are interfacing with a compact or controllogix.  You will have to get out the manual to discover the best way to start/stop and control speed as well as how to get feedback information.  Attached is an example of the Ethernet module setup for the A1000.  Pay careful attention to the comm format data time.  Choose the wrong one and you will have problems.   Not that I have ever done that....
  5. SLC-500 Power Supply Short?

    Given the age of your system, I wouldn't be surprised if the power supply was already going.  They can die in weird ways and one of the things that can happen is that the PLC will drop the program.  Not real fond of the SLC power supplies as they can cause pain and suffering.  They don't seem to just die and that's it.  Every one I've dealt with caused weird problems such as program drops that went away when the power supply was changed.
  6. Why (U) an OTE?

    Sorry I have to respectfully disagree on this.  There is nothing that can be done with the OTU in the situation you mention that could not be done on the rung with the OTE. 
  7. Why (U) an OTE?

    I agree that are uses for the OTU with HMI and SCADA interfaces, but there would be no need for an OTE in such a case.  In addition there should be one OTU with all the conditions grouped on that rung.  That's why OTL/OTU's can be evil!  People place them all over the program and it ends up making one giant mess.  Unfortunately he probably has one of these programs that has evolved over the years with a little here and a little there programming and no attention to the program as a whole.  Nothing like the patched patch of a patch to make your day interesting.
  8. Why (U) an OTE?

    There is no advantage to doing that.   I have seen it before and it screams poor programming practices.  Keep in mind that if you are using a PLC5 or SLC the outputs are not updated until the ladder scan is complete.  In your case, the last unlatch wins.  That can get very ugly.  If you move a rung in your program you can possibly break the program so be very careful with what you do in that program.  That said, I would be looking into the program to see how I could eliminate the OTU's if it were my program.  Keep in mind that depending on the program it could get very tricky. 
  9. DF1 and PLC5 vs SLC500

    I would think that even if the registers were different in the PLC5 versus SLC (ie swapped bytes or something), you would at least get a garbled number.  As I understand you are not getting anything.  That said, even though the cable he posted is wrong, he mentions getting online via RSLinx with autoconfig.  If he has been online with the PLC5 via his cable, then it should be correct. 
  10. studio 5000 ultilzation chalenge

    Ideally you would have some sort of SCADA system that would log downtime events and be setup with scheduled runtime for your machine.  As has been mentioned, you are basically being asked to achieve a poor mans OEE.  As you mention, keeping track of machine run versus stop time is pretty easy.  Joe mentions using the system clock to avoid issues with powering down the controller.  You may also want to add an additional variable to be stored.  Possibly a daily expected runtime number that would allow you to calculate some basic OEE number that has some meaning.  Just logging up and downtimes doesn't let you know if the machine is operating outside its expected run periods (ie, planned downtime versus unplanned downtime). 
  11. DF1 and PLC5 vs SLC500

    Are you sure your communication parameters are correct.  It looks from your text that you are sure about the cable.  The periodic comm light flashing seems to me like a comm port that is trying to connect but not achieving a good connection.  Can you connect up a PC to this port and get online just to insure the cable and comm parameters are correct?
  12. RSLogix5 Analog Scaling

    Actually Michael the SLC isn't from this century either!  LOL
  13. RSLogix5 Analog Scaling

    If you are using the PLC5 you have to scale old school.  Since both of your ranges start at 0 (raw and scaled) then it makes things a little easier.  You can scale at the card level but you lose resolution.  Just use a compute block.  The raw input from an IFE defaults to 0-4095.  0 for 4 ma and 4095 for 20ma.  Hopefully you already have the data transfer from the IFE in the program or it gets a lot harder.  The data from the IFE transfers via a Block Transfer Read (BTR).  You should be able to go into the BTR setup and see the data address associated with your input.  It will be an integer data file such as N7:0.  You can use a compute block (CPT) to do the math.  You will divide your input by 4095 and multiply the result times 50 for your new scale (N7:0/4095*50).  Your destination should go to a floating point such as F8:0.  If your block transfers are not setup then you will probably need to spend some time with the books to get that one figured out. 
  14. SLC5/05 in unmatched chassis

    Ack!  I guess I have been using micrologix controllers too much lately!  I did a quick check before my post but didn't realize that project was a micro.  Glad Mickey stepped up to cover my tracks!  (or any other appropriate word that might go there)
  15. SLC5/05 in unmatched chassis

    Just go into the I/O configuration and click on advanced config for the module that is not there (or double click on it).  You will see a check box "ignore configuration error."  Check that box and you should be able to run your program without faults.