BECKHOFF FC5101 - Manual (Page 48)

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Variable mapping
As a rule, the default mapping of the process data objects already satisfies the requirements. For special types
of application the mapping can nevertheless be altered: the Beckhoff CANopen Bus Couplers, for instance,
thus support variable mapping, in which the application objects (input and output data) can be freely allocated
to the PDOs. The mapping tables must be configured for this: as from Version 4 of CANopen, only the following
procedure is permitted, and must be followed precisely:
1. First delete the PDO (set 0x1400ff, or 0x1800ff, subindex 1, bit 31 to "1")
2. Set subindex 0 in the mapping parameters (0x1600ff or 0x1A00ff) to "0"
3. Change mapping entries (0x1600ff or 0x1A00ff, SI 1..8)
4. Set subindex 0 in the mapping parameters to the valid value. The device then checks the entries for consis-
tency.
5. Create PDO by entering the identifier (0x1400ff or 0x1800ff, subindex 1).
Dummy Mapping
A further feature of CANopen is the mapping of placeholders, or dummy entries. The data type entries stored in
the object directory, which do not themselves have data, are used as placeholders. If such entries are con-
tained in the mapping table, the corresponding data from the device is not evaluated. In this way, for instance, a
number of drives can be supplied with new set values using a single CAN telegram, or outputs on a number of
nodes can be set simultaneously, even in event-driven mode.