Why does the FBox "SASI S-Bus Extended" not work (for assigning a gateway master port)?

FAQ #101399

 

Symptom
When re-assigning a Gateway master port using this FBox (or even in IL with the instruction SASI) it is not possible to assign the same port as Gateway master port after it has once been unassigned. This is the case if there is a falling and later on a rising edge on the input "Sasi" of the FBox "SASI S-Bus extended". On the second attempt to assing the port as gateway master port the FBox will get an error and the FBox LED becomes red:

• In the case you configure the GATEWAY funtion (in the device configurator and in the "SASI S-bus Extended" Fbox )
• The 1rst rising edge on the "SASI" input assigns the communication port (as serial master gateway)
  --> the Master-Slave communication works well.
• A falling edge (state "1" to "0") on ths "SASI" input de-assigns the corresponding communication port
  --> no communication is possible
• If you apply a 2nd rising edge on the "SASI" input, it will put the "SASI S-Bus Extended" FBox in ERROR. 
  A "Cold Start" is required in order to (re-)assign the communication port as serial Master Gateway port.

Reason
IT IS NOT ALLOWED TO DE-ASSIGN A MASTER GATEWAY PORT (an to re-assign it again) on Saia PCD® COSinus systems (PCD3, PCD2.M5, PCD1.M2 and PCD2.M480). This phenomenon is based on the internal mechanism how the firmware assigns the port. It has not been observed before the usage of the FBox "SASI S-Bus extended" as there are very few (if at all) reasons for un- and re-assigning a port as gateway master port.


Solution
In the case you configure the GATEWAY function (in the device configurator and in the "SASI S-Bus Extended" FBox )
WE RECOMMEND YOU TO CONNECT THE "SASI" TO A BINARY CONSTANT "1".

In this way the above mentioned problem will not occur. Please let us know in case you have an installation where it is required to re-assign a port in runtime as gateway master port.