toolman

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  1. Ground the 24VDC Power Supply Common?

    Point well taken! I was addressing a typical manufacturing environment. However, we also have battery operated equipment with instrumentation. These systems are all isolated from the frame including the battery. In your case with a generator you have to deal with a whole host of issues most of us are lucky enough to avoid. For the benefit of other readers here, be careful when selecting a power supply when isolation is needed. Not all supplies provide this and simply not grounding one of the outputs does not give you isolation from the inputs. Even transformer supplies have isolation issues. If all you need is DC isolation then most transformer supplies will suffice. If you need AC isolation then look into ferro-resonant supplies. They are more expensive but if the application requires it they are a good solution.
  2. Ground the 24VDC Power Supply Common?

    Let me offer my 2 cents. If you take a switching power supply with no load and measure from the case to either DC output terminal you will get about 60vac or (AC input)/2. When you install this ps in a panel this voltage shifts depending on the impedances of the circuit. If you unground this power supply then you run a risk of exceeding the common mode voltage limitations of analog circuits. If you ground this power supply then you are attenuating this common voltage problem by keeping the dc- of the supply at the machine ground potential. This can cause a problem with small signal (millivolt) measurements. What I have been doing is using a linear supply for analog and a switching supply for control. I know this is controversial in some circles but if the measurements are critical then this is the solution I have found to be the most effective. I have a machine I was working on today that we decided to remove the switchmode supply and run only a linear supply. The linear supply has more heat gerneration due to the lack of efficiency but it is the superior solution given the requirements. The majority of installations will work fine with switching supplies. In answering your question: Linear supplies: ungrounded Switching supplies: grounded
  3. E5ZN Communications Problem

    Update: Lesson learned: Never make assumptions. I was assuming that the RS485 port was an auxillary port that could be used simultaneously with the devicenet unit. There is only one communications bus and when the devicenet unit is plugged in it takes control of the bus and polls the other modules. This is the datastream I was seeing. When I unplugged the DeviceNet unit, communications to CX-Thermo started working. Thank you for your assistance.
  4. E5ZN Communications Problem

    I initially disagreed with you since the operation manual is showing terminals 23 & 24 as RS485 host which would be correct for connecting to a PC. On another datasheet is see the same terminals defined as RS485 (for temperature controller expansion). Is there a way to have both DeviceNet and RS485 to a PC at the same time?
  5. E5ZN Communications Problem

    I am trying to connect a pc running CX-Thermo (Part of CX-One) to an E5ZN temperature controller. This controller already has an SDL connected to it. I have tried two different RS232-RS485 adapters and I still get a connect error. I had some conversion IC's in my shop so I built my own and was looking at the data stream when I noticed that the E5ZN is continuously outputing a datastream. This datastream appears as garbage in hyperterminal regardless of the settings. (Yes, I am familiar with the protocol) If the E5ZN is a slave device that responds to queries from the host then why am I seeing this datastream? I am using E5ZN-DRTDC24 SDL E5ZN 3 ----- 22 4 ----- 21 PC Adapter E5ZN 2 ----- | TD + | --- 23 3 ----- | RD - | --- 24 5 ----- | SG | I have already tried swapping polarity
  6. AD003 stops running

    The last time around we changed the cpu, expansion rack, cable, modules and no luck. This was the point where we went to the CS1 expansion rack. Yes, I have checked and re-seated all modules and cables. Unfortuanatley, since I cannot recreate the problem, an oxidized contact could have already been addressed. When the problem occurs the production run must be scrapped. And since we are already shut down our current plans are to replace the main rack. All suggestions have been greatly appreciated. If the problem comes back I will update with another post.
  7. AD003 stops running

    The system has been running in this configuration since 12/2004. However, we are having the same problem we had back then. See my posting from 12/04 http://forums.mrplc.com/index.php?showtopic=3259&hl The problem disapeared after changing the expansion rack from a C200H to a CS1 rack (back in 2004). We have taken the line out of production so we can do some testing and recreate the situation but we can't get it to fault again.
  8. AD003 stops running

    System Overview CS1 Rack (10 slot) C200H-PA204S Power Supply CS1 CPU 44 with SCB21 serial module AD002 M0 DA003 M1 CT021 M3 CT021 M4 OA122 OA122 IA122 OC224 ID212 CS1 Expansion cable 12 meter CS1 5 slot rack C200H-PA204S Power Supply AD003 M6 - This one drops out of run mode DA003 M7 - Outputs stop responding to the program OC224 ID212 This is an intermittant problem. Problem happened twice overnight and went away after cycling power. System has been running fine so far today. CPU fault history showed an IO verification error but all equipment checks OK.
  9. AD003 stops running

    What can cause an analog module to drop out of run mode?
  10. CX-Supervisor

    I use Component One ActiveX controls. http://www.componentone.com
  11. What is the update rate of the dde server? If the server is trying to update faster than it can get the data then you can get this problem. If this is the case then slow down the server update rate.
  12. clock and display

    Use the clock adjustment instruction. Date(735) D10 Where: D10, High byte = Minutes, Low byte = Seconds D11, High byte = Day, Low byte = Hour D12, High byte = Year, Low byte = Month D13, High byte = 00, Low byte = Day of week
  13. clock and display

    Hi, Try the following logic. XFRB #0780 A352 D1 (Moves hour into high byte of D1) XFRB #0708 A351 D1 (Moves minute into low byte of D1) This assumes that D1 in the NT11 is setup to display BCD. (this logic is from a CS1 program)
  14. Relay Vs. Trans. outputs - What's the difference?

    Fusing is always a good idea.
  15. Relay Vs. Trans. outputs - What's the difference?

    The program does not care if it is AC or DC. That is a hardware requirement. First make a complete list of all input and output devices listing the voltage and current requirements of each. Are devices AC, DC or mixed? Switches can be either one. Pick the modules by hardware requirements.