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Simon

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Posts posted by Simon

  1. I have encountered this before, but I can't find the specific notes on what I did to "fix" it.

    However, I am reasonably sure it is necessary to hold SB193 ON for a period of time, not just set it as a one-shot. The example in U90 Ladder help shows a direct contact being used.

    My familiarity with modem comms also helps, as I am aware that deleting SMS messages from the modem must be done by sending the modem one command per message to be deleted. The commands take between half a second and one second each, so to delete 20 messages, SB193 should be on for about 20 seconds.

    I hope this helps.

  2. Did you do the OS update via USB (COM1) or Ethernet?

    The OS will always update OK via ethernet, but sometimes the BinLib and Boot files also need to get updated, and this doesn't happen when using Ethernet. You can then have a PLC with incompatible firmware files. The exact problems this may cause will depend on the versions of the files.

    You need to use the USB (or COM1 serial) to update the BinLib and Boot files. I can't say whether that is the cause of this specific issue, but it is something to check and be aware of. I mention it because you say the problem started after an OS update.

    • Upvote 1
  3. Hi, I see where you are coming from. I can see it may work the way you say, but that will need the valve signal input to be fully isolated. So you would set Vout1 (connected to -valve) at 5V to give a reference point, then raise or lower Vout0 (connected to +valve) to give -5V...+5V relative to the Vout1.

    However I still think an external isolator is the most robust method, and simple to understand for you and anyone else who needs to maintain the system.

  4. The short answer to your suggested fix is "no".

    The keyword that needs to be understood is "galvanic isolation".

    The analogue ouputs on the E2B share a common. If they were fully isolated from each other you could use one output for the positive, connected the normal way. For the negative you would need to connect the second output in reverse. This is only possible if the two outputs have their own commons (0V) AND are fully galvanically isolated from each other. The relevant aspect of Galvanic isolation in this case means no continuity between their 0V terminals. THis is not the case with the module you have. You would also need the valve inputs to be fully isolated.

    IF the input of your valve is galvanically isolated, then you could use a voltage divider circuit (with resistors) to create a "virtual" 0V point that is in the middle of your 0...10V span. This requires that the 0V input on the valve is not connected internally to the valve housing or the 0V of the valve power supply.

    The third option is to purchase an EX-A2X and IO-AI4-AO2, which gives you a +/- 10V analogue output.

    Another option is to use an external analogue isolator, configured for 0...10V input and -5...+5V output.

  5. If you needed to swap the bytes in the PLC, as far as I can see you can do it in two steps:

    1. Use the "Vector" -> "Struct" block to take the MF bytes and copy to a DW. This copies the bytes as they are, instead of interpreting them as a number

    2. Use the "Vector" -> "Swap Bytes" Function and use the "32-bit" option to swap the upper and lower words of the DW value.

    To read the value via SCADA you have two options

    • Use the SCADA "read float" function, but point it to the address of the DW in the PLC

    OR

    • Use the "Vector" -> "Struct" block again to copy the bytes of the new modified float back into an MF register (note this will show a strange number when viewed as a float in Visilogic, becuase the words have been swapped). Then point the SCADA function to the MF register.

    I hope this helps.

    • Upvote 1
  6. Hi Cara,

    The MJ10-22-CS32 does come up in the helpfile, however there is no diagram or pinout. You have posted the MJ10-22-CS25 pinout. The MJ10-22-CS32 is the cable required to connect a PC to a Wavecom Fastrack modem for initialisation, or to use as a PC-side modem. I wouldn't really expect it to be in the help since Wavecom have fallen out of favour as a supported modem. However we still have a lot of them in the field and working.

    My pinout table is currently hand-written on the relevant page of the Wavecom manual, which I should not post for copyright reasons. If needed I can transcribe to generic form.

  7. ASCII format would be another option, but it is tied to the SMS functionality. The M90-T does not support SMS.

    The next fallback is to use the PCOM protocol and create a PCOM request using the V130. The PCOM protocol is available here:

    http://www.unitronics.com/Downloads/Support/Technical%20Library/Vision%20Software%20Miscellaneous/Miscellaneous/Communication%20with%20Unitronics%20PLCs.pdf

    This could be time-consuming if you are not familiar with serial protocols.

  8. The Modbus should work via the USB port/COM1.

    However you need to initialise the PLC as a Modbus slave, regardless of what port you use.

    This needs a Modbus Config block and a Modbus Scan block (in general terms).

    Check the Examples in the help menu for Modbus slave for the exact details. You won't find one written directly for the V1040, but use the one provided and convert it to a V1040 project. The display will look a little odd, but the logic should work fine. Just make sure the Modbus configuration is configured for COM1.

    I hope this helps.

  9. It sounds like one of your thermocouples always reads -0.1C regardless of temperature.

    As Alex suggests, the scehamtic is not going to tell you much.

    I would check:

    * swap thermocouples to ensure they are both working

    * ensure the thermocouple is connected with the correct polarity

    * configure another thermocouple input on the same PLC.

    The most likely problem is a faulty probe, incorrect/faulty wiring or configuration error. If those can be conclusively eliminated, then perhaps there is a faulty input on the PLC, but that is the least likely, based on my experience.

  10. Both of my esteemed colleagues appear to have missed the point of the question.

    Firstly, I assume you mean the V1040 (you typed V1020).

    There is the ability to set a splash screen that displays as soon as power is applied, to cover the black and white text that shows during the boot process.

    This is described in the help, search for the term "Splash" and go to the "System Images" topic. You will need to perform a download to make the splash screen active.

    If you want the splash screen to display for longer, also add the same image to the !Startup Display in your program, as per Joe's instructions.

    • Upvote 2
  11. Generally when selecting analogue outputs, it is necessary to be aware of any loop-power requirements. I have dealt with other brands of I/O systems, and the default offering is usually for auxiliary powered devices. If loop power is required then a specific analogue output module must be used. This is at least the case in industrial automation, it may be different in other industries where loop power may be more the norm.

    As far as I know, Unitronics devices do not provide analogue loop power on their outputs.

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