X20 system modules • X20 electronics module communication • X20CS1030
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X20 system User's Manual 3.10
Configuration
The Forward function only has to be enabled for the input direction. Two additional configuration registers are
available for doing so. FlatStream modules have been optimized in such a way that they support this function. In
the output direction, the Forward function can be used as soon as the size of the OutputMTU is specified.
Number of unconfirmed sequences
Name:
Forward
With the "Forward" register, the user specifies how many unacknowledged sequences the module is allowed to
transmit.
Recommendation:
X2X Link:
Max. 5
POWERLINK:
Max. 7
Data type
Value
USINT
1 to 7
Default: 1
Delay time
Name:
ForwardDelay
The "ForwardDelay" register is used to specify the delay time in µs. This is the amount of time the module has
to wait after sending a sequence until it is allowed to write new data to the MTU in the following bus cycle. The
program routine for receiving sequences from a module can therefore be run in a task class whose cycle time is
slower than the bus cycle.
Data type
Value
UINT
0 to 65,535 [µs]
Default: 0
Sequence 1
Sequence 2
Sequence 3
Step I
Step II
Step III
Step IV
Step V
Zeit
Zeit
Sequence 1
Sequence 2
Sequence 3
Step I
Step II
Step III
Step IV
Step V
Step I
Step II
Step III
Step IV
Step V
Step I
Step III
Step IV
Step V
Step I
Step II
Step III
Step IV
Step V
Step I
Step II
Step III
Step IV
Step V
Step II
Bus cycle 1
Bus cycle 2
Bus cycle 3
Bus cycle 4
Bus cycle 5
Bus cycle 6
Bus cycle 7
Bus cycle 8
Bus cycle 9
Bus cycle 10
Bus cycle 1
Bus cycle 2
Bus cycle 3
Bus cycle 4
Bus cycle 5
Bus cycle 6
Bus cycle 7
Bus cycle 8
Bus cycle 9
Bus cycle 10
Figure 505: Effect of ForwardDelay when using FlatStream communication with the Forward function
In the program, it is important to make sure that the CPU is processing all of the incoming InputSequences and In-
putMTUs. The ForwardDelay value causes delayed acknowledgment in the output direction and delayed reception
in the input direction. In this way, the CPU has more time to process the incoming InputSequence or InputMTU.
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