Process Data Objects (Pdo) - ABB FCAN-01 User Manual

Communication protocol 113

Process Data Objects (PDO)

Process Data Object (PDO) is used for time critical process data
exchange. PDO transmissions can be controlled by an internal
timer, by remote requests or by the received Sync message. For
each PDO the transmission mode of the PDO as well as the
default mappings of the application objects are described in the
Object Dictionary. The adapter module supports also configuration
of the PDOs with drive parameters.
The adapter module supports a maximum of three PDOs in both
directions. By default only Tx PDO1 and Rx PDO1 are enabled
(valid) and Tx/Rx PDO6 and Tx/Rx PDO21 are disabled (not valid).
PDO mapping defines which application objects (parameters) are
transmitted within a PDO. PDO mappings of the adapter module
can be changed in the Pre-operational state (variable objects).
Transmission of the enabled (valid) PDOs is possible only in the
Operational state.
Each PDO can contain up to 8 bytes of process data. In ACS355,
the first mapping entries of Tx/Rx PDO1 and Tx/Rx PDO6 are fixed
and cannot be changed. The length of the PDOs and mapping
entries of the PDOs are configurable.
The mapping entries of the PDOs can be configured through
CANopen objects or from the drive with fieldbus configuration
parameters. The configuration location is selected from the drive
with parameter 04 CONF LOC of the fieldbus configuration group
A (group 1) (parameter 51.04 in ACS355, ACSM1, ACS850 and
ACS880).
When mapping through CANopen objects, the PDO length must be
set to zero before the mapping entries can be changed.