Mitsubishi Electronics FX1S Battery backed/ latched counters, Selecting the counting direction

FX Series Programmable Controllers Devices in Detail 4

4.10.2General/ Latched 32bit Bi-directional Counters

FX1S

FX1N FX2N FX2NC

The counter shown in the example below, activates when its coil is driven, i.e. the C200 coil is driven. On every occasion the input X14 is turned from OFF to ON the current value or current count of C200 is incremented.

X12 Up counting					Up counting
			Down counting
X13
X14					X12
						M8200
Counters					X13	RST C200
	4 5
present		4
value	2 3		3 2		X14	C200
0	1		1 0		0
			-1 -2		C200	K-5
					-5 -4-3	Y1
If output is already			-3 -4-5
Y1 turned ON				-6	-7 -8-7 -6

The output coil of C200 is set ON when the current value increases from “-6” to “-5”. However, if the counters value decreases from “-5” to “-6” the counter coil will reset. The counters current value increases or decreases independently of the output contact state (ON/OFF). Yet, if a counter counts beyond +2,147,483,647 the current value will automatically change to -2,147,483,648. Similarly, counting below -2,147,483,648 will result in the current value changing to +2,147,483,647. This type of counting technique is typical for “ring counters”. The current value of the active counter can be rest to "0" (zero) by forcibly resetting the counter coil; in the example program by switching the input X13 ON which drives the RST instruction. The counting direction is designated with special auxiliary relays M8200 to M8234.

Battery backed/ latched counters:

•Counters which are battery backed/ latched are able to retain their status information, even after the PLC has been powered down. This means on re-powering up, the latched counters can immediately resume from where they were at the time of the original PLC power down.

Available devices:

• Please see the information table on page 4-19.

Selecting the counting direction:

•If M8✰✰✰ for C✰✰✰ is turned ON, the counter will be a down counter. Conversely, the counter is an up counter when M8✰✰✰ is OFF.

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