FX3U Series Programmable Controllers
User’s Manual - Hardware Edition
217
11 Use of High-speed Counters (C235 to C255)
11.8 Conditions for Hardware Counter to be Handled as Software Counter
11
High-Speed
Counters
12
Output Wiring
13
Wiring for
Various Uses
14
Test Run,
Maintenance,
Troubleshooting
15
IInput/Output
Powered
Extension Units
16
Input/Output
Extension
Blocks
17
Extension
Power Supply
Unit
18
Other Extension
Units and
Options
19
Display Module
20
Terminal Block
11.8 Conditions for Hardware Counter to be Handled as Software Counter
The high-speed counters are classified into hardware counters and software counters.
Some hardware counters are handled as software counters depending on the operating conditions.
In this case, use hardware counters within the range of maximum response frequency and total frequency
determined for software counters.
11.8.1 Conditions under which counters are handled as software counters
The hardware counters can perform counting with the hardware of FX3U regardless of the overall frequency.
However, under the following conditions, they are handled as software counters.
When using them in the condition below, the maximum response frequencies and overall frequency of the
counters are considered to be the same as those of other software counters.
11.8.2 Method of confirming operation status of counters
The high-speed counter mode, hardware or software, can be confirmed by checking whether the operation
status (M8380 to M8387) is on or off.
→ For the list of operation status of high-speed counters, refer to Subsection 11.11.1.
Hardware
counter No.
Conditions under which counters are handled as software counters
C235
C236
C237
C238
C239
C240
C244(OP)
C245(OP)
C246
C248(OP)
C251
C253
When DHSCS (FNC 53), DHSCR (FNC 54), DHSZ (FNC 55) or DHSCT (FNC280) instruction is
used for a hardware counter number, the hardware counter is handled as a software counter.
Ex.: C235
In this case, C235 works as a software counter.
When the index register is used for the counter number designated by DHSCS (FNC 53), DHSCR
(FNC 54), DHSZ (FNC 55) or DHSCT (FNC280) instruction, all hardware counters are handled as
software counters.
Ex.: C235Z0
When the logic is reversed by the external rest input signal logic change function, C253 (hardware
counter) is switched to a software counter.
Ex.: The logic of the external reset input signal of C253 is inverted.
→ For the inversion of the logic of external reset input signal,
refer to Subsection 11.11.2.
DHSCS K100 C235 Y000
C235
K
DHSCS K100 C235Z0 Y000
M8388
M8389
C253
K
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