Glossary

substation, slave, server

Synonyms for a subordinate station (which is monitored)

Central station, control station, master, client

Synonyms for a higher-level station (control station, monitors others stations)

control direction

Data transfer direction from the central station to the substation

monitoring direction

Data transfer direction from the substation to the central station

application objects

IEC information objects in the TwinCAT PLC application (single points, double points, measured values, short floating point values etc.)

APDU

Protocol data unit of the application layer (application protocol data unit)

APCI

Protocol control information of the application layer (application protocol control information)

ASDU

Service data unit of the application layer (application service data unit)

IOA, address of the information object

Address of the single point, double point, etc. (information object address)