6 — CANopen COMMUNICATIONS
Curtis Model 3301T Digital Instrumentation – September 2021
pg. 48
The following table lists the control byte values for the various transfer types:
Transfer Type
Command Byte
Write data to a device
Depends upon the data size:
• 1 byte = 2Fh
• 2 bytes = 2Bh
• 3 bytes = 27h
• 4 bytes = 23h
Confirm a write
60h
Request data from a device
40h
Device responds with requested data
Depends upon the data size:
• 1 byte = 4Fh
• 2 bytes = 4Bh
• 3 bytes = 47h
• 4 bytes = 43h
Abort SDO
80h
PDOs
TPDOs 1–2 and RPDOs 1–3 are preconfigured to transmit and receive data used by the
3301T-7001’s preset user interfaces. The following topics describe PDO considerations and the
preconfigured PDOs.
Note: TPDOs 3–4 and RPDO4 are reserved.
PDO COB-IDs
The following table lists the COB-IDs of the preconfigured PDOs:
PDO
COB-ID
RPDO1
22Eh
RPDO2
32Eh
RPDO3
42Eh
TPDO1
1AEh
TPDO2
2AEh
PDO Timing
The 3301T's PDOs are asynchronous and are periodically transmitted and received. The 3301T does
not support synchronous PDOs. The following list describes the PDOs’ event times:
• RPDOs: 60,000ms (1 minute). If the 3301T does not receive data within one minute, the LCD
will display *.* to indicate that data is not being received.
• TPDOs: 40ms