Festo CTEU-CO Manual, Functions And Maintenance page 13

Installation
Term/abbreviation
Operating voltage
PDO
PLC/IPC
RPDO
SC/O
SCS, SCO, SCV
SDO
Status bits
TPDO
Voltage supply
Tab. 0/1: Terms and abbreviations
Festo P.BE-CTEU-CO-OP+MAINT-EN en 1101NH
Meaning
also referred to as signal voltage: includes the power supply for
electronics and sensors
Process Data Objects serve for the fast transfer of processing data via
Multicast connection and are transmitted by simple CAN messages
without protocol overhead. Process Data Objects can be transmitted
event-controlled, synchronous to a system pulse sequence or on demand.
PDOs are divided into TPDOs and RPDOs.
Programmable logic controller/industrial PC
Receive PDO
Short circuit/overload
Short circuit/overload sensor supply, outputs, valves
Service Data Objects predominantly form point-to-point connections
between the server and client for the exchange of parameters for device
configuration. They enable write and read access to any entry in the object
directory of a bus node.
Internal inputs which supply coded common diagnostic messages.
Transmit-PDO
Umbrella term for operating and load voltage supplies
XI