Mitsubishi Electric MELSEC FX3U - Page 126

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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.8 High Speed Counter [C] (FX3G PLCs)
5. High speed counter device list
*1. C248 and C253 are usually used as counters having reset input, but can be used as counters C248
(OP) and C253 (OP) not having reset input when used together with special auxiliary relays M8388
and M8392.
→ For the method to switch the counter function, refer to Subsection 4.8.7.
*2. C254 is usually used as a counter having reset input and start input, but can be used as a counter
C254 (OP) not having reset input or start input when used together with special auxiliary relays M8388
and M8395.
→ For the method to switch the counter function, refer to Subsection 4.8.6.
Notation of high speed counter devices
In some high speed counters in FX
3G PLCs, the input terminal assignment is changed over when used
together with special auxiliary relays.
Such high speed counter devices are classified below. Note that description as (OP) is not available in
programming.
Classification Counter No. Data length
External reset
input terminal
External start
input terminal
1-phase
1-count input
C235
C236
C237
C238
C239
C240
32-bit
bi-directional
counter
Not provided Not provided
C241
C242
C243
Provided
Not provided
C244
C245
Provided
Provided
1-phase
2-count input
C246
C248(OP)
*1
32-bit
bi-directional
counter
Not provided Not provided
C247
C248
Provided
Not provided
C249
C250
Provided
Provided
2-phase
2-count input
C251
C253(OP)
*1
C254(OP)
*2
32-bit
bi-directional
counter
Not provided Not provided
C252
C253
Provided
Not provided
C254
C255
Provided
Provided
Standard Device
Numbers
Switched Device Numbers
C248 C248(OP)
C253 C253(OP)
C254 C254(OP)