Encoder module: Sporadic encoder error directly at switch-on (corrected from June 2022)
Corrected from:
Servo inverter i950, feedback module (I9MAG3V...): the encoder modules with modified hardware are available from June 2022 (series conversion).
Response of the new version:
The initialisation of an unexpected offset is reliably avoided by a hardware improvement. The encoder error during start-up no longer occurs.
What happens?
Sporadically, an encoder error (0x29007303) is detected directly after switching on the i950.
In index 0x2C42:4 Encoder settings: Act. amplitude signal quality, the display value deviates significantly from the expected value 100% +/- and varies greatly. The condition for the encoder monitoring to respond is therefore permanently fulfilled.
The error message can only be reset by switching the unit to mains. After switching the i950 to mains, the encoder evaluation works again as expected.
The motion axis (in the i950 or also higher-level) reacts to the encoder error as expected by resetting the status "reference-known".
When does the behaviour occur?
By means of a feedback module (I9MAG3V...) in slot A or slot B, any SinCos encoder is evaluated.
When initialising the encoder module during start-up, an unexpected offset is stored in the AD converter module. This can occur sporadically depending on the transient behaviour of various internal supply and reference voltages, but has only been observed/proven once.
An electrical load on the i950's internal supply voltages during start-up stabilises the transient response of the internal supply and reference voltages in the encoder module.
With the following measure, an electrical load can be generated that reliably prevents the occurrence of the behaviour:
Connect digital input terminals that are not used for the application with high level (+24V).
The behaviour clearly distinguishes itself from other causes of an encoder error:
The encoder error occurs sporadically directly at switch-on when the inverter is still disabled, i.e. it is not a source of interference.
If another SinCos encoder is connected, whose SinCos signals are demonstrably error-free, the encoder error is still reported and 0x2C42:4 shows unexpected values:
The behaviour can only be eliminated by switching the i950 off.
High-level digital inputs of the i950 avoid the occurrence.
Typically, one wired digital input is sufficient
Transitionally, a C-type of individually packaged encoder modules (pre-series of the modified hardware) can be ordered:
I9MAG3V000000S (Encoder-Feedback-Modul) 13620921 Mod i950
SinCos-Hiperface-TTL PU01
