turck DeviceNet RM-89, Руководство пользователя

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Presetting the Position Value
Presetting the value involves the following sequence:
1) Write the Preset Value as a double integer to the first four bytes of the output data assigned to the RM-89 .
2) Set the command byte to a value of “2” .
3) Hold this value until you are sure the scanner module has transmitted the command byte to the RM-89 .
4) Set the command byte to a value of “13” (D
hex
) .
The RM-89 will respond by setting the position value to the Preset Value . At this point, the RM-89 will transfer position and
velocity data over the DeviceNet network .
Saving Offset and Parameters to Flash
The offset that results from a Preset command is stored in RAM memory and is lost when power is cycled to the RM-89 . The
same is true for parameter values . This is acceptable for applications that reset the position value on every power up or
decide to configure the RM-89 on every power up using explicit messaging .
If your application requires absolute position you can issue a save to Flash memory command using the following sequence
with I/O Messaging .
5) Set the command byte to a value of 20
hex
.
6) Hold this value until you are sure the scanner module has transmitted the command byte to the RM-89 .
7) Set the command byte to a value of D0
hex
.
The RM-89 will respond by saving the internal position offset and all parameter values to Flash memory . At this point, the
RM-89 will transfer position and velocity data over the DeviceNet network . If you were transferring some data other than
velocity, you must reset the command word as shown table 4 .1 on page 30 .
The Flash memory of the RM-89 is guaranteed for 10,000 write cycles . A non-recoverable memory error can occur at any time
once this value is exceeded . If you need to preset the position often and require it to remain after a power cycle, you have
two options:
1) Set the Total Measurement Range parameter to a non-zero value, such as its maximum value for your
RM-89’s configuration . If this is done, the RM-89 will automatically store the position offset into FRAM
memory instead of Flash . FRAM memory is non-volatile so the position will remain absolute over a power cycle .
Additional information, including information on the maximum value of the Total Measurement Range, can be
found in the Non-Volatile Memory section of the manual starting on page 12 .
2) Calculate, store, and apply a position offset that is stored in the PLC .