SD7 trip on some Hiperface absolute value encoders SKM36/SKS36 (eliminated as of V8.0 on 9300ES/EP/EK, ECS as of OPERATING SYSTEM V8.3)

Which products are affected?
9300ES servo controller as of V8.0
9300EP position controller as of V8.0
9300EK CAM profiler as of V8.1
9300 Servo PLC as of V8.0
ECS Application OPERATING SYSTEM as of V8.3

Eliminated function restrictions
The initialisation sequence for Hiperface absolute value encoders has now been thoroughly revised and fully optimised. The functional restriction caused by the occurrence of SD7 TRIP faults has been eliminated as part of this process.
The analysis of the prevailing SD7 problems identified the differences in the timing behaviour of encoder and controller during initialisation as the underlying cause. Therefore, Hiperface communication during initialisation has been made more secure with regard to the differences in timing. The changes made include the sending of two reset commands from controller to encoder within a specific time interval. This all but synchronises the initialisation of encoder and controller. The encoder absolute position is then read out reliably in the time range permitted by the encoder.

Another advantage:
The current firmware revision has achieved a further reduction of 50% in the total initialisation time of the controller with Hiperface absolute value encoder:
- Before: approx. 3.0 s
- After: approx. 1.5 s

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Which products are affected?
9300ES servo controller <= V7.0
9300EP position controller <= V7.0
9300EK cam <= V7.1
9300 servo PLC <= V7.2
ECS Application OPERATING SYSTEM  <= V8.0

What happens?
Fault Sd7-TRIP can occur on some Hiperface absolute value encoders, primarily the SKM36/SKS36 type by Sick/Stegmann, after initialisation (mains connection).

When does the problem occur?
As soon as first commissioning after mains switching, but not necessarily on all SKM36/SKS36 type Hiperface encoders and devices.
Whether or not an SD7-TRIP actually occurs clearly depends on the applicable component tolerances and the resulting timing behaviour.

Diagnostics options?
SD7-Trip occurs even though the Hiperface encoder appears to be operational.

Short-term measures/recommendations?
Use a different type of Hiperface encoder, e.g.: SRM50/SRS50.

Evaluation:
The drive behaviour described does not pose an acute danger, as the drive remains in the fault state and does not move.

URL for linking this AKB article: https://www.lenze.com/en-de/go/akb/200803980/1/