MELSEC-A Series Positioning Unit HOLD Error Technical Bulletin

This technical bulletin provides remedies for the "HOLD error" (error code 51) occurring on Mitsubishi MELSEC-A Series positioning units (AD71, A1SD71-S2, A0J2-D71). The error is caused by uncleared buffer memory after purchase or low/disconnected battery voltage, and can be resolved by all-clearing the buffer memory, resetting the PLC CPU, and rewriting positioning data.