Fluctuating analog values are due to screening on the connecting wire from the analog
valuator device to the analog AM2 / AM2 PT100 / AM2 RTD LOGO! expansion module
(encoder wire) that has either been mounted incorrectly or not at all.
To avoid fluctuating analog values when using these expansion modules, proceed as
• Use only shielded encoder wires.
• Shorten the encoder wire as much a possible. The encodeer wire must not be more than
10 meters long.
• Clamp the encoder wire on one side only and clamp it only to the PE terminal on the AM2
/ AM2 PT100 / AM2 AQ / AM2 RTD expansion module.
• Connect ground on the encoder supply to the PE terminal on the expansion module.
• Avoid operating the LOGO! AM2 PT100 or LOGO! AM2 RTD expansion module with a
power supply that is not grounded (potential-free). If you cannot avoid this, connect the
negative output/ground output on the power supply to the shielding on the resistance
thermometer's measuring wires.
Manual, 10/2017, A5E01248535-AA
LOGO! installation and wiring
2.3 Wiring LOGO!