A33421 — Encoder 3: Coarse position error

The manuals give this message two titles: Encoder 3: Coarse position error and Encoder 3: Determined commutation position incorrect (alarm). Both describe the same condition: while sensing the commutation position actual value, the drive detected an error and must therefore assume that the actual value sensing is supplying an incorrect coarse position. Which sensing error occurred is stored as an alarm value in r2124, to be interpreted as a decimal number; for this code the manuals describe alarm value 3. Depending on how the drive is configured, the same condition can also be output as a fault or as a message without a reaction.

• A commutation position actual value sensing error was detected at Encoder 3, so it must be assumed that the actual value sensing supplies an incorrect coarse position.
• Alarm value 3: the absolute position of the serial protocol and track A/B differ by half an encoder pulse. The zero position of the absolute position must lie in the quadrants in which both tracks are negative; in the case of a fault, the position can be incorrect by one encoder pulse.

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

• The message value %1 is the alarm value; the drive stores it in r2124, to be interpreted as a decimal number. For this code the manuals describe only alarm value 3.
• 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 here, interpreted as a decimal number, to identify the sensing error behind A33421; value 3 means the absolute position of the serial protocol and track A/B differ by half an encoder pulse.

A33421 is an alarm: the drive takes no automatic reaction and the message does not have to be acknowledged. If the drive configuration outputs the same condition as a fault instead, that fault must be acknowledged immediately.