F33126 — Encoder 3: Amplitude AB too high

F33126 reports that the signal level of Encoder 3 is above the permissible limit. The drive monitors the two incremental tracks A and B and responds when the sum of their magnitudes (|A| + |B|) exceeds 1120 mV, or when the amplitude — the root of A^2 + B^2 — exceeds 955 mV. For a healthy encoder, the nominal signal level lies between 375 mV and 600 mV (500 mV -25/+20 %).

The G130/G150 manual titles the code «Encoder 3: Amplitude AB too high», the S120/S150 manual «Encoder 3: Signal level track A or B too high»; both describe the same condition on the same component, so the page treats them together. Depending on how the drive is configured, the identical event can also be output only as an alarm or entirely without reaction.

• The signal level of the encoder — the sum of the magnitudes of track A and track B (|A| + |B|) — exceeds the permissible limit value; the G130/G150 manual words the same cause as the amplitude (root of A^2 + B^2 or |A| + |B|) for Encoder 3 exceeding the permissible tolerance.

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

The message value contains the amplitude and the angle. The drive stores them in the fault value r0949; interpret the value hexadecimal as yyyyxxxx:

• yyyy = Angle
• xxxx = amplitude, i.e. the root of A^2 + B^2 (16 bits without sign)
• Nominal signal level of the encoder: 375 mV to 600 mV (500 mV -25/+20 %)
• The response threshold is reached when (|A| + |B|) exceeds 1120 mV or the root of (A^2 + B^2) exceeds 955 mV
• A signal level of 500 mV peak value corresponds to the numerical value 10650
• The angle 0 ... FFFF hex corresponds to 0 ... 360 degrees of the fine position; zero degrees is present at the negative zero crossover of track B
• The amplitude and angle are not captured at the same instant as the hardware fault output: The analog values of the amplitude error are not measured at the same time with the hardware fault output by the Sensor Module.

• r0949 — fault value: for this code read it as a hexadecimal yyyyxxxx number, where the lower four digits xxxx give the measured amplitude (root of A^2 + B^2, 16 bits without sign) and the upper four digits yyyy the angle.

Acknowledge the fault in PULSE INHIBIT mode: the pulse inhibit must be active before the drive accepts the acknowledgment. In practice the sequence is: let the drive's stop response bring the motor to a standstill, clear the condition on the encoder, acknowledge the fault, then restart. When the same event is configured as an alarm or with no reaction, the drive takes no action and nothing has to be acknowledged.