MITSUBISHI ELECTRIC MELSERVO MR-J2S- A - Manual (Page 146)

5 - 27
5. PARAMETERS
(b) Conveyor setting example
For rotation in increments of 0.01 per pulse
Machine specifications
Table : 360 /rev
Reduction ratio: n 4/64
Servo motor resolution: Pt 131072 [pulses/rev]
Table
Timing belt : 4/64
Servo motor
131072 [pulse/rev]
CDV
CMX Pt 131072 65536
1125
0.01
4/64 360
................................................................................. (5.2)
Since CMX is not within the setting range in this status, it must be reduced to the lowest term.
When CMX has been reduced to a value within the setting range, round off the value to the
nearest unit.
CDV
CMX 65536
1125
26214.4
450
26214
450
Hence, set 26214 to CMX and 450 to CDV.
POINT
When “0” is set to parameter No.3 (CMX), CMX is automatically set to the
servo motor resolution. Therefore, in the case of Expression (5.2), setting
0 to CMX and 2250 to CDX concludes in the following expression:
CMX/CDV=131072/2250, and electric gear can be set without the
necessity to reduce the fraction to the lowest term.
For unlimited one-way rotation, e.g. an index table, indexing positions will
be missed due to cumulative error produced by rounding off.
For example, entering a command of 36000 pulses in the above example
causes the table to rotate only:
26214
450
36000
1
131072
4
64
360 359.995
Therefore, indexing cannot be done in the same position on the table.
(2) Instructions for reduction
The calculated value before reduction must be as near as possible to the calculated value after
reduction.
In the case of (1), (b) in this section, an error will be smaller if reduction is made to provide no fraction
for CDV. The fraction of Expression (5.1) before reduction is calculated as follows.
CDV
CMX 65536
1125
58.25422.................................................................................................................... (5.2)
The result of reduction to provide no fraction for CMX is as follows.
CDV
CMX 65536
1125
32768
562.5
32768
563
58.20249 .................................................................................... (5.3)
The result of reduction to provide no fraction for CDV is as follows.
CDV
CMX 65536
1125
26214.4
450
26214
450
58.25333.................................................................................. (5.4)
As a result, it is understood that the value nearer to the calculation result of Expression (5.2) is the
result of Expression (5.4). Accordingly, the set values of (1), (b) in this section are CMX 26214,
CDV 450.