The 691HT handheld controller cannot communicate
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The laboratory purchased several 691HT handheld controllers 5 years ago. When they were used again a few days ago, it was found that none of the controllers could communicate (they were connected to ABB differential pressure transmitters, so the problem lay not with the transmitters or the connections). I wonder if any of you know what the cause might be; please share your insights!
After all, it’s a ABB product; it can’t be that bad, right? Have you read the instruction manual?
The system isn’t compatible with the hardware, after all, it’s from a few years ago.
Is it the Hart protocol? Has a resistor been added to the circuit? Is the operator panel addressing mode set correctly?