User manual

C - 68 Magelis

7. Description of dialog-table words

 Communication monitoring

This word is incremented every dialog-table write cycle. When it reaches

65535 it does not pass through 0, but immediately takes the value 1.

The word can be used as a watchdog for the display unit: If it is not

incremented regularly, it can be assumed that the display unit is no

longer operational. Finally, this word can take the value 0 when the

display unit is powered up and whenever communication is restarted,

but never takes the value 0 thereafter: It can therefore be used by the

synchronization pilot equipment to detect starting up of a display unit or

restarting communication.

XBT -> PLC Communication monitoring

XBT ref. Note

0 (first cycle in the dialog table)

or restarting communication

65535

cycle