F01688 — SI Motion CU: Actual value synchronization not permissible

F01688 is raised in the Control Unit (CU) when the SI Motion safety function "actual value synchronization" is enabled in a combination that is not permissible. The manual names three such combinations: enabling the function for a 1-encoder system, enabling it simultaneously with a monitoring function with absolute reference — SCA (Safe Cam) or SLP (Safely Limited Position) — and enabling it simultaneously with "Safe position via PROFIsafe". Both list manuals that describe this fault state the same causes and the same remedy, and both note that the fault results in a STOP A that cannot be acknowledged.

• Actual value synchronization has been enabled although the drive is a 1-encoder system.
• Actual value synchronization and a monitoring function with absolute reference — SCA (Safe Cam) or SLP (Safely Limited Position) — are enabled simultaneously.
• Actual value synchronization and "Safe position via PROFIsafe" are enabled simultaneously.

1. Establish which combination is parameterized: the SI Motion safety functions are enabled at the Control Unit via p9501, and the encoder of the second SI Motion channel is assigned via p9526.
2. If actual value synchronization is enabled for a 1-encoder system: either parameterize a 2-encoder system or deselect the "actual value synchronization" function.
3. If actual value synchronization is enabled together with a monitoring function with absolute reference (SCA/SLP): deselect either the "actual value synchronization" function or the monitoring functions with absolute reference, and then carry out a POWER ON.
4. If actual value synchronization is enabled together with "Safe position via PROFIsafe": either deselect the "actual value synchronization" function or do not enable "Safe position via PROFIsafe".

• p9501 — SI Motion enable safety functions (Control Unit): the parameter with which the SI Motion safety functions are enabled at the Control Unit; this is where "actual value synchronization" or a conflicting monitoring function has to be deselected so the fault can be remedied.
• p9526 — SI Motion encoder assignment second channel: the assignment of the encoder to the second SI Motion channel; the manual refers to it when the remedy is to parameterize a 2-encoder system instead.

This fault results in a STOP A that cannot be acknowledged, so the message cannot simply be reset while the impermissible combination is still parameterized. First remove the combination — deselect "actual value synchronization" or the conflicting function, or parameterize a 2-encoder system — and then carry out a POWER ON, which is the acknowledgement the remedy prescribes for this fault.