cupoftea
Advanced Member level 5
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Hi,
Just today seen a big test jig with unshielded ribbon cable comms wires and it was working intermittently. I suspect noisy comms. There was an approx 15way ribbon cable (approx 30cm long) between 2 boards. Can you confirm that the comms signals in this need to be differnetial type?, and not the unipolar (TTL) type that you commonly see between components that are near to each other on the same board? So, eg, the ribbon cable should contain eg CAN bus signals, or RS485?, rather than TTL?
The test jig was for a switching circuit for three phase mains.
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Also, presumably on a test jig, which will not be made in volume, you should do super-low-bit-error-rate comms?.....eg, the most noise immune comms protocol that exists? With the highest magnitude signals (bits), so that SNR is maximised?
Also, common mode chokes should be used at each end of the cable to reduce bit error rate?
Also, shielded cable will reduce bit error rate?
And if its ribbon cable then it must have GND interleaved with all signals? (to reduce BER)?
BTW, what is the comms protocol with the lowest BER?
Presumably slower comms will always be less noisy than faster comms?.......and if possible, comms should be slowed down so much that the comms lines can be RC filtered?
Just today seen a big test jig with unshielded ribbon cable comms wires and it was working intermittently. I suspect noisy comms. There was an approx 15way ribbon cable (approx 30cm long) between 2 boards. Can you confirm that the comms signals in this need to be differnetial type?, and not the unipolar (TTL) type that you commonly see between components that are near to each other on the same board? So, eg, the ribbon cable should contain eg CAN bus signals, or RS485?, rather than TTL?
The test jig was for a switching circuit for three phase mains.
..............................-----------------...............................
Also, presumably on a test jig, which will not be made in volume, you should do super-low-bit-error-rate comms?.....eg, the most noise immune comms protocol that exists? With the highest magnitude signals (bits), so that SNR is maximised?
Also, common mode chokes should be used at each end of the cable to reduce bit error rate?
Also, shielded cable will reduce bit error rate?
And if its ribbon cable then it must have GND interleaved with all signals? (to reduce BER)?
BTW, what is the comms protocol with the lowest BER?
Presumably slower comms will always be less noisy than faster comms?.......and if possible, comms should be slowed down so much that the comms lines can be RC filtered?
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