Hi all,
S7-300, CPU 315-2 DP. PROFIBUS DP at 1.5 Mbit/s, eleven slaves, ET 200M stations and three MICROMASTER 440. Ran clean for twelve years.
Last month the electricians extended the segment to a new packing line, two more ET 200M and an MM440. Segment is now about 300 m by the drum count.
Since then the three new slaves and the last old one drop out a few times an hour. The diagnostics buffer fills with "distributed I/O: station failure" and BF flashes on the far stations, solid on the near ones. I've checked the termination at both ends and swapped the connector on station 14, no change.
Do I need to lower the speed, or is one of the new stations pulling the bus down? It ran twelve years and only started since the extension, so where would you start on a segment that long?
Same thing on the old press. We had a profibus run that started doing exactly this after an extension, and it turned out the electricians had used a different cable for the new bit, looked the same colour under the lid. Is the new bit the same part number as the old, off the same drum?
Same drum, same part number, I checked the print on the jacket. Old run and new run are both 6XV1830-0EH10, so it isn't the cable type. Baud rate is set in HW Config on the DP master system, 1.5 Mbit/s, and nobody's touched it.