Product specifications

Controller Data Exchange
3BDS011222-510 B 315
Controller Data Exchange
Process Interface
An SDL Log collects process values as properties from controllers on the control
network. For secured retrieval of these process values, a specific protocol between
SDL Collector and PLC control logic must be implemented. This protocol is based
on a Trigger property (type VT_I4) and an Acknowledge property (type VT_I4).
PLC starts data collection by raising a command bit in the TRIGGER property and
the SDL Collector acknowledges the data collection through ACKNOWLEDGE
property. This protocol is described in Data Exchange Protocol on page 319.
It is also possible to use a simple protocol without Acknowledge property. See Data
Exchange Protocol Without Acknowledge on page 321.
STATE ACTION
1 SDL Collector locates enabled SDL Log aspects that refers to the
service. A service is referred through the SDL LogType of SDL Log
aspect.
2 SDL Collector subscribes TRIGGER properties of SDL Log aspects.
3 SDL Collector waits for 'Data Changed' event on TRIGGER's.
4 SDL Collector reads all the properties of data record.
5 SDL Collector checks the OPC Quality of mandatory properties.
6 SDL Collector returns to state 4 if the OPC Quality is bad for any of the
mandatory properties.
7 SDL Collector stores the properties in the database as one data record
and returns to state 3.
The SDL Collector will loop indefinitely through state 4, 5, and 6 if a mandatory
property persistently returns bad OPC Quality.