Curtis 1356 - PDO Communications Protocol; PDO Data Transmission and Mapping

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Curtis 1356/1356P CAN Expansion Module Manual, Rev. A
4 — PDO COMMUNICATIONS
4
PDO COMMUNICATIONS
e PDO (Process Data Object) communication packets conserve bus band-
width by bundling the values of a group of objects into a single message. e
1356 /1356P is controlled and monitored through four PDOs. PDO messages
have a medium priority and each PDO always carries 8 bytes of data. e content
of these PDOs can be dynamic mapped as Curtis AC motor controllers. For
PDO dynamic mapping information, please refer to Curtis document Generic
CANopen Implementation.
A PDO transfers 8 bytes of data across the CAN bus. Any given byte is
mapped to a single byte of a pre-dened CAN Object. Mapping can be done
statically as part of the system design, or it can be done “dynamically” by us-
ing SDO transfers. Dynamic mapping is implemented on the 1356 /1356P, as
described in Section 5: SDO Communications.
PDO-MISO messages can be transmitted either in Cyclic Transmission
mode or in standard Master/Slave mode.
e Cyclic Transmission mode
allows the 1356 /1356P to periodically
transmit the PDO-MOSI at the programmed cycle rate. e cycle rates are ad-
justable via two parameters: TPDO1 Cycle Rate (for PDO1-MISO) and TPDO2
Cycle Rate (for PDO2-MISO). If the rate is set to 0, the Cyclic Transmission
mode will be disabled and only the standard Master/Slave mode will be available.
In standard Master/Slave mode
, the 1356 /1356P requires the PDO-MOSI
to be cyclic from the master. e cycle time must be less than the programmed
PDO Timeout. If the PDO-MOSI is not received within the programmed
time, the 1356 /1356P will ag a PDO Timeout fault and disable all output
drivers. If the PDO Timeout parameter is set to 0, the PDO Timeout fault is
disabled and the 1356 /1356P will respond to any PDO incoming at any rate
without faulting.
e following tables describe the PDOs exchanged with default mapping.
PDO1-MOSI (received from the system master)
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
Output 1 Output 2 BDI [Reserved] [Reserved] [Reserved] [Reserved] [Reserved]
Command Command (0–100%)
PDO2-MOSI (received from the system master)
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
[Reserved] [Reserved] [Reserved] [Reserved] [Reserved] [Reserved] [Reserved] [Reserved]