Pulse Width/Pulse Period Measurement Function (Supported In Ver. 1.10 Or Later); Allocation Of Special Memories To Input Numbers; Cautions For Pulse Width/Period Measurement Function - Mitsubishi Electric MELSEC-F FX3G Series User Manual

FX Series Programmable Controllers
3G
User's Manual - Hardware Edition
10.6 Pulse width/Pulse period measurement function
(Supported in Ver. 1.10 or later)
Four input points in the PLC (main unit) can be used for the pulse width/period measurement function which
enables measurement of the pulse width or pulse frequency in units of 10 s.

10.6.1 Allocation of special memories to input numbers

Input number
measurement flag
X000
X001
X003
X004
*1. Cleared when PLC switches from STOP to RUN.
*2. The pulse width which can be measured is a minimum of 10 s and a maximum of 100 s.
The pulse period which can be measured is a minimum of 20 s and a maximum of 100 s.

10.6.2 Cautions for pulse width/period measurement function

1. Non-overlap of input numbers
The input terminals X000, X001, X003 and X004 can be used for high-speed counter, input interruption, pulse
catch, speed detection (SPD) instructions and general-purpose input.
Take care not to overlap the input numbers.
However, overlap of input numbers is allowed for input interruptions.
2. When the pulse width/period measurement function and high-speed counters are used
together, the overall frequency of high-speed counters is affected.
3. Make sure that the total frequency of four input channels is 50 kHz or less when using the
pulse width/period measurement function.
4. Cautions in wiring
It is recommended to use shielded twisted-pair cables for connection cables.

10.6 Pulse width/Pulse period measurement function (Supported in Ver. 1.10 or later)

→ For details on programming, refer to the programming manual.
Pulse period
Pulse width/
measurement
Pulse period
mode
M8076 M8080
M8077 M8081
M8078 M8082
M8079 M8083
→ For details on programming, refer to the programming manual.
Ring counter value for Ring counter value for
*1
rising edge falling edge
[in units of 1/6 s] [in units of 1/6 s]
D8075, D8074 D8077, D8076
D8081, D8080 D8083, D8082
D8087, D8086 D8089, D8088
D8093, D8092 D8095, D8094
→ For more details, refer to Section 11.7.
10 Input Wiring Procedures
Pulse width/
*1 *1*2
Pulse period
(in units of 10 s)
D8079, D8078
D8085, D8084
D8091, D8090
D8097, D8096
159
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