Unitronics PCOM Protocol
Unitronics PCOM Protocol
This describes the telegrams used to communicate data between PC and OPLC.
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It looks like no damage on inputs before galvanic isolation. In my lab only connector Snap-in to PLC make problems some times. You can try to install faulty Snap-in to anothe PLC for test. Having some experience in using an oscilloscope and reading the manuals for the applied microcircuits, you can determine how the parallel-to-serial converter works and understand at what stage the circuit stopped working. However, this is probably meaningless - it is easier to replace the module with a new one, since they are in production. P.S. It would be interesting to play with a module broken in this way, but I have not come across modules with such a problem. I have already studied the operation of analog outputs, which had to be repaired after 220VAC voltage was applied there. I can say that galvanic isolation saved the PLC and I managed to get everything back to working order. -
Thanks Kratmel I found the two fuses for analog in and HS out. On the inputs with diode selected on the meter for I0 to I3 i get 1.056 for all other inputs i get 1.330. The board looks very clean with no signs of corrosion. Regards Denis -
If someone cares to take a look, I implemented a few ideas from your comments on this video thanks -
Totally agree with you, so far I added a max run time to trigger one alarm, jump to a display then pick from a list and assign this to a MAX Run Time cause. Next thing is to have a LOW PRESSURE ALARM but I am struggling with the noise again, thinking about getting a different power supply. The comparator fails to trigger an alarm with 1 second timer Run time accumulator for each compressor is also in the works. Thanks!
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No. No fuses installed in input cirquitry. But two fuses installed for analog output and HS output - you can find it. In Snap-in installed PS2705 or similar optocoupler for all inputs. You can test faulty unit inputs for both separated channel input group I0-I8 and I9-I17 Use multimeter in diode checking mode - all standard input to COM wire must show 1500-1800 readout - the same for both direction. HS inputs has lower readout then reular inputs. If tested ok - module internal cirquit (parallel-to-serial convertor) damaged. Please check internal circuit for corrosion.
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