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Contents
This allows a coil to control a specific function in the drive. You could
use bit manipulation instructions operating on word 40100 (such as
MBIT), but it is far simpler to just assign coils to specific functions, and
then move these coils into the Control Word. These coils are then moved
into word 40100 using the simple instruction shown below:
Now the user may control specific functions by turning on and off these
coils. For example, to start the drive, the user would turn on coil 15,
which is block moved to word 40100, setting Modicon bit 15 on.
Register 40100 is then transmitted over Modbus Plus via the Peer Cop
to the 1560-MBP, which then turns on bit 1 in the drive control word,
starting the drive. Inputs 100001-100016 may then be examined to
observe feedback, such as run acknowledgment.
Note that by using this approach, the complexity is minimized by setting
up a control structure (peercop) up front once, which may now be easily
copied and duplicated. Also, additional drives may be very easily
controlled by simply adding a few entries to the peercop tables and a
block move to transfer bit states to the drive.
Special Precautions and hints
Timing
Because all parameters to and from the drive must pass through the
SCANport, be careful about adding additional devices, such as the HIM
module, when critical drive communication timing is required. While it
does not affect the transfer of parameters, it does affect the throughput,
which may cause unexpected problems in speed critical applications.
Other devices placed on the network will affect the speed of the Modbus
Plus network. Programming panels and operator interfaces can add
significant network load. Nodes going online or off-line momentarily
disrupt the token passing pattern. For critical drive control, a separate
dedicated Modbus Plus network is recommended.
enable -
abort -
400110
- active
00001
BKLM
00001
- error
- success
Appendix C — Peer Cop Example
