Handling Of High Speed Counters; Current Value Update Timing And Comparison Of Current Value; Related Devices - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4.8.3

Handling of high speed counters

High speed counters in FX
For details, refer to the following.
4.8.4

Current value update timing and comparison of current value

1. Current value update timing
When pulses are input to an input terminal for a high-speed counter, the high-speed counter executes up-
counting or down-counting. The current values of devices are updated when counting is input.
2. Comparison of the Current value
The following two methods are available to compare and output the current value of a high speed counter.
1) Using the comparison instruction (CMP), zone comparison instruction (ZCP) or comparison contact
instruction
Use the comparison instruction (CMP), band comparison instruction (ZCP) or contact comparison
instruction if the comparison result is necessary at counting. Use these instructions only when high-speed
processing is not required because these instructions are processed in the operation cycle of the PLC,
and operation delay is generated before the comparison output result is obtained.
If it is necessary to execute comparison to update an output contact with the high-speed counter's
changing value, use comparison instructions for high speed counters HSCS, HSCR and HSZ.
2) Using comparison instructions for high speed counters (HSCS, HSCR or HSZ)
The comparison instructions for high speed counters (HSCS, HSCR and HSZ) execute a comparison and
output the comparison result during high speed counting. The number of times these instructions can be
used is limited as shown in the table below.
When an output relay is specified for the comparison result, the comparison result is directly updated at
the ON/OFF status of the output regardless of the output refresh by END instruction.
Mechanical operation delay (about 10 ms) cannot be avoided in a relay output type PLC. Use a transistor
output type PLC.
Instruction
HSCS
HSCR
HSZ
4.8.5

Related devices

1. Devices used to switch the counting direction of 1-phase 1-count input counters
Type
1-phase
1-counting input
126
PLCs operate in the same way as high speed counters in FX
3G
Limitation in number of instruction
Can be used up to 6 times.
Counter No. Specifying device
C235
C236
C237
C238
C239
C240
C241
C242
C243
C244
C245
→ 4.7.3 Handling of high speed counters
Up-counting
M8235
M8236
M8237
M8238
M8239
M8240 OFF
M8241
M8242
M8243
M8244
M8245
4 Devices in Detail
4.8 High Speed Counter [C] (FX3G PLCs)
/FX
3U
Down-counting
ON
PLCs.
3UC