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marcob
@marcob
New Member
Joined: Jan 29, 2025
Last seen: Sep 19, 2026
Topics: 1 / Replies: 7
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RE: Modbus TCP over LTE, half of twelve wellpad RTUs time out every poll cycle

How many registers per site, one block or several? And are the twelve polled one after the other, or all at once?

17 minutes ago
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RE: Roof fan VFD trips overcurrent at start when the wind is up

Enabled flying start last night. Windy this morning, wheel going backwards steady. Start went in, the display showed a negative frequency, swung throu...

22 minutes ago
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RE: Modbus RTU RS-485 to six meters on a MicroLogix 1400, timeouts on the far three

Two problems, both classic. Idle voltage near zero at the far end means there's no bias anywhere, so the line floats and the far receivers read noise ...

3 hours ago
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RE: Modbus exception 02 illegal data address reading a flow computer with S7-1200 MB_CLIENT

Off by one is my first guess always, 47001 in the block being register 7000 on the wire. You've tried both sides, fine. Post the manual page for those...

4 hours ago
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RE: Modbus TCP through a serial gateway, exception 0B or no reply from every slave

255 is the problem. On most straight TCP devices the unit ID is decoration, they'll answer to anything. Through a serial gateway it's the only thing t...

8 hours ago
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RE: MB_CLIENT on S7-1200 reads the wrong registers from a power meter, values shifted

Off by one, the oldest Modbus problem there is and I have lost days to it myself. The manual's 3000 is the protocol address, counting from 0. MB_CLIE...

10 hours ago
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RE: Roof fan VFD trips overcurrent at start when the wind is up

Instant. Zero on the display, trip, nothing in between. No idea about DC brake, I've never been into that group on a 525 and I'd rather not guess at i...

2 days ago