N33415 — Encoder 3: Amplitude alarm track A or B (A^2 + B^2)

Encoder 3 is evaluated as a pair of tracks A and B, and the quantity the drive monitors is their combined signal level — the square root of A^2 + B^2. When this amplitude leaves the permissible window, the drive signals N33415 for encoder 3. For a sinusoidal encoder the nominal signal level must lie between 375 mV and 600 mV (500 mV -25/+20 %); the response threshold is below 230 mV, and the frequency response of the encoder has to be observed. For a resolver evaluated through a Sensor Module — for example an SMC10 — the nominal signal level is 2900 mV (2.0 Vrms) and the response threshold is below 1414 mV (1.0 Vrms).

The same condition can also be issued as a fault (F) or as a plain alarm (A); which form the drive outputs depends on its configuration. In the form printed here it is a message that leaves the drive running.

• The amplitude of the encoder signals — the root of A^2 + B^2 — has moved outside the permissible tolerance around the nominal signal level.

1. Check the speed range: the frequency characteristic (amplitude characteristic) of the measuring equipment may not be sufficient for the speed range in use.
2. Check that the encoder cables and their shielding are routed in compliance with EMC.
3. Check the plug connections.
4. Check the Sensor Module, for example its contacts.
5. Replace the encoder or the encoder cable.
6. If the coding disk is soiled or the lighting has aged, replace the encoder.

• The message value reports the amplitude and the angle. Both are stored in r2124, which is read as hexadecimal yyyyxxxx: yyyy is the angle, xxxx is the amplitude, i.e. the root of A^2 + B^2 (16 bits without sign).
• For scale: a signal level of 500 mV peak value corresponds to the numerical value 10650 decimal, and a resolver level of 2900 mV peak value corresponds to 3333 hex = 13107 decimal.
• The angle 0 ... FFFF hex covers 0 ... 360 degrees of the fine position; zero degrees is present at the negative zero crossover of track B.
• The analog amplitude values are not captured at the same time as the hardware fault output of the Sensor Module.

• r2124 — the alarm value of this message: read hexadecimal, its upper digits hold the angle and its lower four digits the measured amplitude of tracks A and B.

As this message, the condition needs no reset: the drive keeps running and the message clears itself once the signal level is back inside the tolerance window. If the drive has been configured to raise the same condition as a fault, that fault is cleared by an immediate acknowledgement once the cause has been remedied.