F31125 — Encoder 1: Amplitude error track A or B overcontrolled

F31125 reports that the signal level of Encoder 1 — the combined amplitude of both tracks, the root from A^2 + B^2 — exceeds the permissible limit value. On S120 and S150 the message is titled Encoder 1: Signal level track A or B too high; on G130 and G150 the same condition appears as Encoder 1: Amplitude error track A or B overcontrolled.

The nominal signal level of the encoder must lie in the range 375 mV to 600 mV (500 mV -25/+20 %); the drive raises the fault once the level exceeds 750 mV. For Sensor Modules for resolvers (e.g. SMC10) the nominal signal level is 2900 mV (2.0 Vrms) and the response threshold is above 3582 mV. Depending on how the drive is configured, the same condition can also be issued as an alarm (A) or as a message with no reaction (N).

Note that the analog values of the amplitude error are not measured at the same time as the hardware fault output by the Sensor Module.

• The signal level (root from A^2 + B^2) of encoder 1 exceeds the permissible limit value — expressed for G130 and G150, the amplitude of track A or B exceeds the permissible tolerance band.
• Per the G130/G150 description, this fault also occurs if the analog/digital converter is overcontrolled.

1. Check that the encoder cables and shielding are routed in compliance with EMC.
2. Replace the encoder or the encoder cable.

The drive stores the measured levels of both tracks in the fault value (r0949), which is to be interpreted as a hexadecimal value yyyyxxxx:

• yyyy — signal level, track B (16 bits with sign)
• xxxx — signal level, track A (16 bits with sign)

Reference points: a signal level of 500 mV peak value corresponds to the numerical value 5333 hex = 21299 dec; for Sensor Modules for resolvers (e.g. SMC10), a level of 2900 mV peak value corresponds to 6666 hex = 26214 dec. The message value itself reads A track: %1, B-track: %2, so %1 is the level of track A and %2 the level of track B.

• r0949 — fault value: read the measured signal levels here, interpreted as hexadecimal yyyyxxxx, to see track A (xxxx) and track B (yyyy).
• p0491 — motor encoder fault response ENCODER: the parameter the manual points to for the drive's response to this encoder fault.

The fault must be acknowledged before the drive will restart; the acknowledgment is by pulse inhibit (PULSE INHIBIT). If the same condition is configured as a message without reaction (N), the manual notes that there is neither a reaction nor an acknowledgment.