pturmel

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Everything posted by pturmel

  1. Siemens

    Mwah, ha, ha, ha! Compare the native languages of the people who designed them.
  2. Measure carefully.  The bulk of the time caused by the diode will be between output turn-off and the valve beginning to close.
  3. Well, the coil is the item storing energy, and producing the reverse voltage when the driving voltage quits.  With a diode, the reverse voltage peaks at ~0.7V.  With an MOV, that reverse voltage peaks at the MOV's breakdown rating. With neither diode nor MOV, that reverse voltage peaks at spark initiation in the wiring, or at the failure reverse voltage of the driving circuit. For the pedants among us engineers. (:
  4. One more note:  when switching solenoid coils that fast, use heavy-duty Metal-Oxide-Varister suppressors on the coils instead of flyback diodes.  Flyback diodes greatly lengthen the time it takes for solenoids to turn OFF.  Probably too much for 10ms cycles.  MOVs apply reverse voltage to the coil such that they turn off about as quickly as they turn on. Some digital output modules from various brands include flyback diodes right in the digital output.  You must not use that kind of output module, for this same reason.
  5. This sounds like a typical PLC application.  You will almost certainly be disappointed trying to switch valves that fast with Modbus RTU.  You will want those coils wired individually to output modules mounted directly to the PLC's CPU. I'm not familiar enough with the Modicon family's motion control capabilities to know if it will be responsive enough.
  6. SAIA PLC - Modbus TCP truncates 32 bit value

    Keep in mind that the floating point format issue is independent of the Modbus protocol issue.
  7. SAIA PLC - Modbus TCP truncates 32 bit value

    The devices I've encountered that use this bastardized Modbus with 32-bit registers simply do not work with standard Modbus.  You might need a custom solution for that PLC, or consider replacing the PLC with something that follows the standard.
  8. Modbus Plus Issues

    That sounds like worn-out hardware.  Electronics don't last forever.  (At the very least, heat makes the P-N doping in the silicon migrate/diffuse, weakening the transistors, until eventual failure.  There are many other failure modes over the long term.) I recommend you start swapping components with spares.
  9. NA5 HMI response time / freezing

    The whole point of a switch (as opposed to a hub) is to maximize overall capacity by only sending unicast packets to the ports having the corresponding MAC id.  So this is normal.  Many lightly managed switches have a "port mirror" feature that changes that for one port to be used for packet captures.  Look for that in that switch.
  10. L18ERM 16#0203

    That's a local module, not a network module.  It is possible that the backplane needs to be taken apart and re-assembled.
  11. Strange.  Should definitely be class 1.  Might be a broken EDS file.
  12. L18ERM 16#0203

    Connection to what?  And what software is showing you that message?
  13. Yeah, but the CPU can have a failure in just its backplane circuits.  Or, since a CompactLogix doesn't have an independent backplane that isolates failures to single devices, any one of your "backplane" modules could be shorting out the comms. Independent of the ethernet. Take your backplane apart.  Put it back together one module at a time, testing with the end cap for each module added.  If you find a failure point, swap the order to confirm which module is the problem.  If you can't get any backplane module to work with that CPU, the CPU's backplane circuit is broken.
  14. You were online with that processor.  Surely you can save a copy while online.
  15. Or just wiggle loose.  I endorse Bob's advice. If that doesn't work, you may have CPU hardware failure.
  16. In the connection tab of the modules' configuration pages, the connection tabs should show live indicators and error codes.  Screenshot them for use to review.
  17. Is the processor's "I/O Ok" light solid green?  What do you mean by "did some simulation" ? Look at the connection status in each I/O module's popup window.
  18. PLC5 Redundancy

    I have never used that module (the 1785-BCM).  But based on a quick review of the user manual, I think you will need to use a DH+ to EtherNet/IP gateway.  Perhaps a ControlLogix chassis with a 1756-DHRIO module plus one of the 1756-EN?T modules.  The user manual doesn't show the PLC-5/LxxE models as compatible.
  19. PLC5 Redundancy

    No, not directly.  That redundancy option only worked with ControlNet processors, not the Ethernet processors.  You might be able to use ethernet side-car modules, but your HMI would have to be smart enough to determine which PLC is the master at any given time.
  20. Where the integrator had both V12 and V13 installed, it sounds like.
  21. The software you choose is dictated by the hardware you choose.  So, you are really asking what hardware we would choose. On the low end, I like AutomationDirect's Productivity series.  I don't mind Rockwell's Micro800 family, but only because the software is free. /: AutomationDirect's drives and servos are functional and inexpensive, but are weak on communication features. I like AutomationDirect's C-More HMIs more than any other pure HMI product.  Reasonably priced, too. In the mid-range, I like Rockwell's CompactLogix family, and Omron's NJ series. On the high-end, I like Rockwell's ControlLogix, and Omron's NX series. Rockwell's drives and servos are decent, but not spectacular, for the price.  I haven't used Omron drives or servos. I've seen some good stuff from Mitsubishi and Keyence, but haven't had an excuse to use them.  Keyence Vision systems are very good. I avoid Siemens processor and networking products like the plague.  (Their drives and servos are pretty good, though.)
  22. None payment demand.

    I have never trapped a PLC or automation system.  But I have had a (very large) company that failed to pay for some work later ask me to expand upon it.  They were shocked when I insisted on being paid for the old work before I'd even touch their stuff.  Must have turned over an anthill internally, because the management there changed soon after.  They still didn't pay, though.  I've not accepted any RFPs from them since. One area where my policy differs is pure software licenses.  I am a third-party module developer for the Ignition platform, and use its infrastructure to license my modules.  I will disable a license if payment is substantially late.  The way the infra works doesn't kill the end-user's operation, until they try to upgrade or add features.  Similar to what happens with real estate when a service company puts a lien on property for unpaid services.  You can't sell the house without satisfying the unpaid bill.
  23. SAIA PLC - Modbus TCP truncates 32 bit value

    I've encountered this before.  It was a technique started by Enron, and persists in some industries.  Most Modbus implementations cannot talk to such non-standard devices.  I believe Kepware supports "Enron Mode".  I don't know of anything else outside the oilfield world.
  24. MODBUS TCP

    Words are integers, so have no decimal, by definition.  The most common way to address this is simply to multiply by ten or one hundred, and transmit with an implicit one or two decimal places.  (Multiply before converting to integer.)
  25. Pretty sure not. Aside from that, what would possess you to put a PLC on a public IP address? { Typical remote access solutions use various VPN technologies to securely move packets between two otherwise insecure endpoints. }