Nidec Unidrive M300 - Write Consistency and Data Transfer Methods

SI-Ethernet User Guide 159
Issue: 3
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7.5.3 Write consistency
Under normal conditions, cyclic data is sampled and written at the Requested Packet Interval (RPI).
However, if an option module was in the process of reading the mapped parameters while these
parameters were being written, then the data obtained may not be consistent across the entire
assembly object. If write consistency is enabled (Out Consistency Enable (S.20.028)) and a trigger
parameter specified in Out Consistency Trigger Param (S.20.029) then new data will only be written
to the drive (or option module) when the trigger parameter Out Consistency Trigger Param
(S.20.029) contains a value of zero. This trigger parameter will then be set to one after the data has
been written.
It is therefore possible, by controlling the trigger parameters, that a user program in the drive or
option module can ensure that the values in the cyclic data parameters are not sampled until all
values are updated.
Whether consistency is enabled or not, data will always be consistent for an individual parameter,
i.e. all 4 bytes of a 32-bit value will be consistent.
Example
In this example, Pr 0.18.031 is set as the input trigger and Pr 0.18.032 is set as the output trigger.
The EtherNet/IP master is configured to check the values of Pr 0.20.011 and Pr 0.20.012 are equal
and write the same value to Pr 0.20.021. The SI-Applications Plus module is configured to generate
a ramp value between -32768 and 32767 to write to Pr 0.20.011 and Pr 0.20.012 when the value of
Pr 0.20.021 is equal to the ramp value.
With the input and output consistency enabled, parameters Pr 0.20.011 and Pr 0.20.012 will be
sampled and transmitted to the EtherNet/IP master when the input trigger parameter Pr 0.18.031 is
a non-zero value, Pr 0.20.021 will be written to when the output trigger parameter Pr 0.18.032 is a
value of zero.
The parameter changes required are:
S.20.020 Input assembly object size = 8 (bytes)
S.20.021 Output assembly object size = 4 (bytes)
S.20.026 In Consistency Enable = On
S.20.027 In Consistency Trigger Param = 0.18.031
S.20.028 Out Consistency Enable = On
S.20.029 Out Consistency Trigger Param = 0.18.032
S.21.001 Input mapping parameter 1 = 0.20.011
S.21.002
Input mapping parameter 2 = 0.20.012
S.22.001 Output mapping parameter 1 = 0.20.021