Common Cautions On Using Instructions For High Speed Counter - Mitsubishi Electric MELSEC FX3U Programming Manual

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

13.4.1 Common cautions on using instructions for high speed counter

DHSCS (FNC 53), DHSCR (FNC 54), DHSZ (FNC 55) and DHSCT (FNC280) instructions are provided for
high speed counters.
This section explains common cautions for these instructions.
1. Limitation in the number of an instruction in a program
1) FX /FX
3U 3UC
DHSCS, DHSCR and DHSZ instructions can be used as many times as necessary in the same way as
general instructions. However, the number of simultaneously driven instructions is limited. The DHSCT
instruction can be used only once in any program.
Instruction
DHSCS
DHSCR
*1
DHSZ
*1
DHSCT
2) FX PLCs
3G
The DHSCS, DHSCR and DHSZ instructions can be used 6 times in total in any program. In addition, the
number of simultaneously driven instructions is limited for these instructions.
Instruction
DHSCS
DHSCR
DHSZ
2. Response frequency of high speed counters
When the DHSZ or DHSCT instruction is used in FX
total frequency of every software counter are limited.
When the DHSCS, DHSCR or DHSZ instruction is used in FX
counters is limited.
3. Specification of output numbers (Y)
When using the same instruction for high speed counter repeatedly or when driving two or more other
instructions for high speed counter at the same time, specify such output devices (Y) whose high-order two
digits are the same (in units of 8 devices).
1) When using devices of the same number (in units of 8 devices)
Example: When using Y000, specify Y000 to Y007. When using Y010, specify Y010 to Y017.
2) When using two or more instructions for high speed counter and non-consecutive output (Y) numbers
A program example is shown below:
M8000
When C255 reaches K100, the output Y000 is driven by interrupt. Y010 is driven when END processing
is executed.
If interrupt drive is required, use an output number in the range from Y001 to Y007 whose high-order two
digits are equivalent.
368
PLC
Limitation in number of instructions driven at same time
32 instructions including DHSCT instruction
Only 1 (This instruction can be used only once.)
Limitation in number of instructions driven at same time
6 instructions (These instructions can be used up to 6 times in total.)
→ For the maximum response frequency and total frequency in FX
→ For the total frequency in FX
FNC 53
K100 C255
DHSCS
FNC 53
K100 C255
DHSCS
13 High Speed Processing – FNC 50 to FNC 59
13.4 FNC 53 – HSCS / High Speed Counter Set
/FX PLCs, the maximum response frequency and
3U 3UC
PLCs, the total frequency of high speed
3G
3G
Y000
Y010
/FX
3U 3UC
refer to Subsection 4.7.10.
PLCs, refer to Subsection 4.8.7.
PLCs,