Count Error - Mitsubishi MELSEC Q Series User Manual

6 CONVENIENT USAGE

6.1.2 Count error

Sampling/cycle time setting value x 10 [ms]
(Sampling/cycle time setting value (unit: 10ms)) Pulse input speed [pps] Multiplier factor [count]
6 - 3
With the counter function selection, an error occurs in the count when it is executed
using an external input (voltage applied to the function start input terminal) or by a
sequence program (counter function selection start command ON).
The following explains how to calculate the count error.
(1) Count error (maximum) due to input response delay when using an
external input
1 [ms]
[s]
pulse input speed [PPS]
1000
(2) Count error (maximum) when the counter function selection is
executed by a sequence program
1 scan time [ms]
1000
(3) Count error (maximum) due to the internal clock when executing
the sampling counter function and periodic pulse counter function
1000
Pulse input speed [pps]
multiple [count]
[s]
pulse input speed [PPS]
Error in parts dimensions, 100 [ppm]
[s]
Multiplier factor [count]
1000000
MELSEC-Q
multiple [count]
1000000
6 - 3