Emerson Unidrive M701 User Manual

SI-Ethernet User Guide 145
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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 (Output
assembly object consistency enable (S.20.028)) and a trigger parameter specified in
Output assembly object consistency trigger parameter (S.20.029) then new data will
only be written to the drive (or option module) when the trigger parameter Output
assembly object consistency trigger parameter (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

Emerson Unidrive M701 Specifications

General

Brand	Emerson
Model	Unidrive M701
Category	Controller
Language	English