Precautions When Using Pulse Outputs - Omron SYSMAC CJ Series User Manual

8 Pulse Outputs
8-10 Precautions when Using Pulse
Outputs
Movement Direction when Specifying Absolute Pulses
When operating with absolute pulses, the movement direction (CW/CCW) is selected automatically
based on the relationship between the pulse output PV when the instruction is executed and the speci-
fied target position. The direction (CW/CCW) specified in an ACC(888), SPED(885), or PLS2(887)
instruction is ignored.
Using CW/CCW Limit Inputs for Pulse Output Functions other than
Origin Searches
Pulse outputs will stop according to the PLC Setup when either the CW or CCW limit input signals turns
ON. It is also possible to select whether the defined origin will be cleared when a CW or CCW limit input
signal turns ON for a pulse output function.
Differences between Set Frequencies and Actual Frequencies
The pulse output frequency of the Pulse I/O Module is determined by dividing the source clock fre-
quency (33,330 MHz) by an integer ratio. Consequently, there may be a slight difference between the
set frequency and the actual frequency.
And that difference increases as the frequency increases. The actual frequency can be calculated from
the following equations.
Pulse Output System
Source clock
33,330 MHz
Equations
Actual frequency (Hz)=
Dividing ratio=INT
The INT function extracts an integer from the fraction. The non-integer remainder is rounded.
8-82
Integer dividing ratio calculated
from user's set frequency
Output pulses (actual frequency)
Frequency divider
Source clock frequency
Dividing ratio
Source clock frequency × 2 + Set frequency
Set frequency (Hz) × 2
CJ2M CPU Unit Pulse I/O Module User's Manual