A31421 — Encoder 1: Coarse position error

A31421 is an alarm from Encoder 1: the drive has detected an error in the actual value sensing, so the position it has determined for commutation — the coarse position — cannot be trusted. The manuals print this code under the titles "Encoder 1: Determined commutation position incorrect (alarm)" and "Encoder 1: Coarse position error". Which sensing error occurred is given as an alarm value in r2124, to be interpreted as a decimal number. Depending on how the drive is configured, the same condition can also be signaled as a fault or with no reaction instead of as this alarm.

• The drive detected a commutation position actual value sensing error on Encoder 1. As a result of this error, it must be assumed that the actual value sensing supplies an incorrect coarse position.

1. Read the alarm value in r2124 as a decimal number and confirm it is 3.
2. If a standard encoder with cable is connected, contact the manufacturer where relevant.
3. Correct the assignment of the tracks to the position value that is serially transferred: the two tracks must be connected inverted at the Sensor Module — interchange A with A* and B with B*.
4. If a programmable encoder is used, check the zero offset of the position.

• The drive writes the alarm value into r2124; interpret it as a decimal number.
• 3 — the absolute position of the serial protocol and track A/B differ by half an encoder pulse; the absolute position must have its zero position in the quadrants in which both tracks are negative. In the case of a fault, the position can be incorrect by one encoder pulse.

• r2124 — alarm value: read it here as a decimal number to identify which sensing error Encoder 1 reported; for this code, value 3 means the serial absolute position and track A/B differ by half an encoder pulse.

As an alarm, A31421 requires no acknowledgement — the drive does not react automatically and the message does not have to be reset. If the drive is configured to signal the same condition as a fault, that fault must be acknowledged immediately; in the no-reaction form, no acknowledgement is required either.