Joe E.

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About Joe E.

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  1. RSLinx Enterprise cannot find PLC

    If they're using RSLinx Classic, yes.  If they're using RSLinx Enterprise, I have no idea but would think not.
  2. RSLinx Enterprise cannot find PLC

    If you go to RSLinx in your start menu, there should be a shortcut to "RSLinx Classic Launch Control Panel".  You can start/stop it there and disable "always run as service".
  3. RSLinx Enterprise cannot find PLC

    If you're trying to connect your RSLogix or Studio 5000 software to the PLC, you will need RSLinx Classic, not Enterprise.
  4. Kind of combine the steps above.  While looking for an instruction that would adjust the precision of the REAL to 2 places, I discovered the TRUNCATE instruction, which strips out the decimal portion very cleanly without using SUB or rounding: The operator would enter 4:45PM as 16.45, the result would be 16.75.  
  5. Choose a PLC

    And the cost of the programming software...
  6. For that, it's probably easiest to convert all of your times back to a REAL, so that 3:30PM becomes 15.50, 2:54PM becomes 14.90, etc.  Then just use a LIM instruction to see if current time is between the start/stop times provided.  Parallel all of the time windows and if any are true, run. For example, if your time is stored in 2 DINT registers, HOUR and MINUTE with TimeNow being a REAL: DIV DateTime[4] 60 TimeNow ADD TimeNow DateTime[3] TimeNow You would do a similar calculation on the manual run windows (or just have the operator enter it in the correct decimal format directly).  Then you could do this: BST LIM FixedStart TimeNow FixedStop NXB LIM ManualStart1 TimeNow ManualStop1 BND OTE Run At midnight, you can just write the value "50.0" (or similar) to all of the ManualStartx and ManualStopx tags.  The TimeNow will never get there, so those LIM instructions will always be false.
  7. The ControlLogix rounds when you move a REAL to a DINT, so you can't just move it to a DINT or 16.59 will become 17.  However, you can subtract: SUB Float_Input 0.5 DINT_Hours I got the minutes in 2 steps: MOD and MUL: MOD Float_Input 1 HoldingRegister01 MUL HoldingRegister01 100 DINT_Minutes HoldingRegister01 is a REAL tag used as an intermediate step You will want to limit check both values to make sure the operator didn't enter something like 16.8 instead of 16.08.  Unless you want them to be able to enter 16.8, in which case you'll need some more complicated code...
  8. Rockwell BootP DHCP Tool

    Every time our IT group upgrades the network (and subsequently makes changes to our laptops to work with it), BOOTP gets less and less reliable.  The least unreliable way I've found is to use a virtual machine with a USB network adapter connected directly to the VM and NO other network connections (NAT, Bridged, host-only, etc.) connected at all.  That seems to work ok.  Most of the time.  Usually.  
  9. SLC500 to Compactlogix Migration

    To what PLCMentor said, even if they're all the same line, be careful combining them into one processor.  We had an engineer do that about 15-20 years ago.  He combined 3 PLC-2 machines into a single PLC-5 by converting 2 of the 1771 racks to RIO (remote IO).  Now, we're faced with a dilemma where we need to replace one of the machines with another one that's a completely different type.  Of course, the machine we're replacing is the one with the now-combined PLC-5 processor in it and we don't have very many PLC-5 CPUs laying around so we can't easily just replace the RIO modules with PLCs.  We're looking at a forced migration with very limited time to do it.  "They" also want the machine we're taking out to remain "intact" and able to be run in another facility so we can't just rob the CPU and re-address the RIO racks. If there's ANY possibility that you might at some time in the future replace just one of the machines and not the others, seriously consider leaving each machine with its own PLC.   We had another machine that originally had a PLC-5 that "they" upgraded to a ControlLogix L55.  They replaced the PLC5 CPU with an RIO module, turning it into a remote chassis of the L55, which was in the same cabinet.  They didn't do a very good job of documenting everything, so when we tried to trace out stuff in the code to figure out which sensor/switch/whatever wasn't happy, it was VERY difficult.  If you turn these SLC 500 racks into remote racks of another PLC, whether it's one PLC for all of them or one PLC for each of them, DOCUMENT, DOCUMENT, DOCUMENT!  Make a detailed cross-reference so it's as easy as possible to correlate the tag in the PLC to the physical IO point.  Your electricians will thank you later...
  10. You want to confirm that the setpoint is valid, even if it doesn't change?    I would set up a "heartbeat" between the SCADA and PLC.  In other words, the PLC turns a bit on, then the SCADA turns it off after a certain time (a few seconds), then the PLC turns it back on.  If either system detects that the bit hasn't changed state after a timeout period, it knows that it isn't talking and needs to respond appropriately. Another option if you can't add a heartbeat bit is to have the DB location that the SCADA writes become an intermediate step with the PLC using a different location for its actual work.  If the SCADA is set up to constantly write the setpoint to that DB, the PLC can periodically clear the DB location and then see that the SCADA re-writes it.  Essentially making a heartbeat out of the setpoint.  If the SCADA only writes the setpoint when it changes, I think you'll have to have a heartbeat bit or some other way to confirm that the PLC and SCADA are communicating.
  11. Merging 2 RSLogix 5000 projects

    We had a system with a 1756-L55 controlling the  main part (it replaced an old PLC2 about 6 years ago) with an older series CompactLogix (serial port, no networking) controlling one section.  We replaced the L55 with an L71 (super easy migration) and the CompactLogix with an -AENT module to turn that into a remote chassis on the L71.  The CompactLogix had only one program and mostly program-scoped tags so moving it into the L71 was relatively easy.  I then just built the CompactLogix chassis in the IO configuration and re-aliased the program tags that referred to the compact IO modules to point to the "new" chassis and it was done.  It took less than an hour to do all of that.  It took the electricians longer to run the network cable than it took to make the program changes.  The L71 is now running 2 programs: the old L55 program and the moved CompactLogix program. I've only done it that once, so I don't have any written instructions to share.
  12. Point I/O compared to Flex I/O

    Yeah, whenever I do scaling with the Flex IO, I have a long rung comment explaining the "magic math" that's going on so the next guy (usually me a year later...) can decipher what the weird numbers are.  You know, something like, "0-80mm = 4-20mA = 0-16xxx counts".  I had to really brute force some basic stuff in an S7-300 that should have been really simple. I left some pretty long rung comments there to explain why I went around the house 3 times to get to the front door.
  13. panelview 300 micro

    I don't think there's a good drop-in replacement for the Micro 300.  What is it talking to?  If what its talking to has Ethernet capability, I would replace it with a Panelview +7 4.3" if it will fit (it's a little bigger).  If the PLC is RS232 only, I would be very tempted to give the Red Lion 4" Kadet another try (we had a lot of trouble with the earlier Kadets so we're a little shy of them now).  I'm pretty sure you won't be able to "convert" the program but will need to build it from scratch.  There may be software I'm not aware of to convert the Panelbuilder 32 file to FT View Studio.     
  14. Point I/O compared to Flex I/O

    My biggest objection to Flex IO in the Logix 5000 world is analog scaling.  Point modules let you scale to engineering  units in the hardware configuration while Flex modules don't.  You have to write your own scaling code, which is made more annoying by the absence of the SCP instruction in Logix 5k. 
  15. Current limit on PLC 5000

    The only time I've had to add an external resistor is in parallel with the device to convert the mA signal to voltage.  That's on an older Eurotherm chart recorder.