Cautions On Use - Mitsubishi FX3U-?*MR/ES User Manual

FX Series Programmable Controllers
3U
User's Manual - Hardware Edition

11.12 Cautions on Use

• If the operation of a high-speed counter is triggered by a device such as a switch, the counter may
malfunction due to extra noise from switch chattering or contact bounce.
• The input filter of an input terminal for a high-speed counter in the main unit is automatically set to 5
(X000 to X005) or 50
Accordingly, it is not necessary to use the REFF instruction or special data register D8020 (input filter
adjustment).
The input filter for input relays not being used for high-speed counters remains at 10 ms (initial value).
• The inputs X000 to X007 are used for high-speed counters, input interrupt, pulse catch, SPD/DSZR/DVIT/
ZRN instructions and general-purpose inputs. There should be no overlap between each input number.
For example, when C251 is used, X000 and X001 are occupied. As a result, "C235, C236, C241, C244,
C246, C247, C249, C252 and C254", "input interrupt pointers I00* and I10*", "pulse catch contacts M8170
and M8171" and "SPD instruction using X000 and/or X001" cannot be used.
• Make sure that the signal speed for high-speed counters does not exceed the response frequency
described above. If an input signal exceeds the response frequency, a WDT error may occur, or the
communication functions such as a parallel link may malfunction.
• The response frequency changes depending on number of used counters, but the input filter value is fixed
µ s (X000 to X005) or 50 µ s (X006 and X007).
to 5
Note that noise above the response frequency may be counted depending on the filter value of the used
input.
228
→ For programming details, refer to the Programming Manual.
µ s (X006 and X007).
11 Use of High-speed Counters (C235 to C255)
11.12 Cautions on Use
µ s