EcoStuxure Control Expert PLC and TeSysT on ProfibusDP: Extended Diagnostic Overflow Explained

On ProfibusDP network during initialization, the PLC (master) always ask slaves for diagnostic data (get_diagnostic telegram).
Slave will respond with diagnostic data.
Diagnostic data can consist of:
- standard diagnostic or
- standard diagnostic + extended diagnostic
Length of standard diagnostic data is fixed, while extended diagnostic is manufacturer-specific and its content and length is defined by manufacturer.
TeSysT serves not only standard diagnostic but also extended diagnostic (manufacturer specific). Max length of diagnostic telegram from TeSysT is 36bytes. Description of vzTeSysT diag telegram is in attachment.
In Control expert, or older Unity software, the profibus modules by default allocate 32bytes for diagnostic telegram which is not enough for TeSysT. It must be increaesed to 36 bytes or more.

Released for:Schneider Electric Singapore