Product specifications

Data Exchange Protocol Without Acknowledge
3BDS011222-510 B 321
• If Retry Counter (RC) reaches maximum value, that can be stored in
TRIGGER word part. If time-out happens, it will wrap to 1. Hence Retry
Counter gets incremented and wrapped within the given protocol cycle.
• The protocol is prepared with a simple transaction control feature. Transaction
Counter occupies 2 most significant bytes of TRIGGER and
ACKNOWLEDGE word. If PLC increments Transaction Counter between
protocol cycles (with wrapping), it is useful to the PC to determine whether a
data package is about to be duplicated or it has been lost.
• Even though this protocol includes an Acknowledge scheme, it does not
support negative Acknowledge. (i.e. PC can not indicate to PLC that the
protocol cycle went well but the data exchange failed).
Data Exchange Protocol Without Acknowledge
The data exchange between the Control network (PLC) and the SDL Collector (PC)
can be governed by the simpler protocol described below.
It is recommended to use the protocol described above.
Figure 193. Data Exchange Protocol without Acknowledge, Simplified Description