Siemens alarm 144*: Zero mark monitoring responded

What it means

Transmission errors, noise or excessive speed caused pulses within one encoder revolution to be lost relative to the zero mark. The zero-mark plausibility failed, so actual-value integrity is doubtful: check encoder pulses and the transmission path, and if necessary switch monitoring off briefly via MD 1820* bit 1 during diagnosis.

Likely causes

• Noisy/damaged encoder cable or shielding
• Encoder traversed above permissible speed
• Failing encoder electronics