Mitsubishi Electric RD77MS2 User Manual page 39

Synchronous encoder via CPU (Synchronous encoder via CPU module)
■Setting method
Used to operate a gray code encoder that is connected to the input module of the CPU module as a synchronous encoder
axis.
By setting "201: Synchronous encoder via CPU" in "[Pr.320] Synchronous encoder axis type", the synchronous encoder is
controlled by the encoder value which is the input value of "[Cd.325] Input value for synchronous encoder via CPU".
The encoder value can be used as a cycle counter within the range from 0 to (Resolution of synchronous encoder via CPU -
1).
Connection is invalid just after the system's power supply is ON. When "1" is set in "[Cd.324] Connection command of
synchronous encoder via CPU", the synchronous encoder axis current value and the synchronous encoder axis current value
per cycle are restored based on "[Cd.325] Input value for synchronous encoder via CPU". Therefore, connection becomes
valid, and will be on the counter enabling status.
The synchronous encoder axis is controlled based on the amount of change of "[Cd.325] Input value for synchronous encoder
via CPU" while it is connecting.
■Setting example
The following shows an example for setting a synchronous encoder via CPU as synchronous encoder axis 4 of the Simple
Motion module.
(Resolution of the gray code encoder: 4096 pulses/rev)
RD77MS
RD77MS4
RUN ERR
3 1
AX AX
4 2
Set "201: Synchronous encoder via CPU" in "[Pr.320] Synchronous encoder axis type" of synchronous encoder axis 4.
Set "4096" in "[Pr.329] Resolution of synchronous encoder via CPU" of synchronous encoder axis 4.
Read the encoder value of the gray code encoder with a program, and update "[Cd.325] Input value for synchronous encoder
via CPU" of the synchronous encoder axis 4 at every time.
■Restrictions
• "[Cd.325] Input value for synchronous encoder via CPU" is taken every operation cycle, but it is asynchronous with the
scan time of the CPU module. Therefore, speed fluctuation of the synchronous encoder axis becomes larger if the refresh
cycle of "[Cd.325] Input value for synchronous encoder via CPU" becomes long. Update "[Cd.325] Input value for
synchronous encoder via CPU" in a cycle less than the operation cycle or use smooth speed fluctuation with the smoothing
function.
• The synchronous encoder current value that is restored for the synchronous encoder connection gets restored into a
converted value from the following range based on the synchronous encoder movement amount on disconnection.
Setting value of "[Pr.329]
Resolution of synchronous
encoder via CPU"
1 or more
0 or less
*1 If the resolution of a synchronous encoder via CPU is an odd number, round down a negative value after the decimal point, round up a
positive value after decimal point.
Input
module
Axis 1
Range of restored synchronous encoder current value
-(Resolution of synchronous encoder via CPU / 2) to (Resolution of synchronous encoder via CPU / 2 - 1) [pulse]
-2147483648 to 2147483647 [pulse]
Axis 2 Axis 3
2.2 Synchronous Encoder Axis
Gray code
encoder
Synchronous encoder axis 4
*1
2 INPUT AXIS MODULE
2
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