Hitachi NJI-350B manual High-Speed Counter Single-Phase, Operation of Single-Phase Counter

Chapter 8 High-speed counter, PWM / Pulse train output and Analogue I/O

8.2 High-Speed Counter (Single-Phase)

The high-speed counter settings are stored in the special internal outputs (WRF070 to 7E). It is only possible to perform the setting through the special internal output (WRF071) when the CPU is stopped and the output is turned off. Once all the input/output settings are completed, the settings of each counter can be changed using the special internal outputs for individual setting (WRF058 to 5B), regardless of whether the CPU is operating or stopped. In addition, the settings can be changed by a program using the FUN instruction (FUN140 to 142, and 146). Refer to the chapter about the FUN instruction for information about how to use the FUN instruction for setting.

8.2.1 Operation of Single-Phase Counter

(1)Basic operation

Figure 8.5 describes the basic operation of the high-speed counter.

FFFFH

Off preset

2]

3]

4]

On preset

0000H

U:Up counter

D:Down counter

Coincidence ON

output OFF

1]	7]		5]
			6]
U	U	D	U	U	D
	D			D

R7FC to R7FF	ON
Coincidence	OFF
interrupt	ON

n:Even number OFF

m:Odd number

1]

On preset

2]

Off preset

INT2n INT2m	INT2n	INT2n INT2m	INT2n INT2n INT2m			INT2n	INT2n		INT2m
	4]
	Off preset				Each coincidence interrupt
Coincidence interrupt				Coincidence interrupt	and INT number
occurrence				occurrence		Counter 1		At on-preset		INT20
Coincidence output On				Coincidence output On				At off-preset		INT21
						Counter 2		At on-preset		INT22
	5]
								At off-preset		INT23
	On preset					Counter 3		At on-preset		INT24
								At off-preset		INT25
Coincidence interrupt				Coincidence interrupt		Counter 4		At on-preset		INT26
								At off-preset		INT27
occurrence				occurrence
				Coincidence output Off
Coincidence output Off

Figure 8.5 Basic operation of high-speed counter (single-phase)

Up counter

1] The counter output turns on* when the current counter value becomes larger than the on-preset value. The interrupt process (INT2n) starts up if an interrupt program is used in the running user program.

2] The counter output turns off when the current counter value becomes larger than the off-preset value. The interrupt process (INT2m) starts up if an interrupt program is used in the running user program.

3] The counter values wrap around in a ring. That is, the current counter value goes back to 0h when one more pulse is counted after the maximum value (FFFFH) is reached.

Down counter

4] The counter output turns on* when the current counter value becomes smaller than the off-preset value. The interrupt process (INT2m) starts up if an interrupt program is used in the running user program.

5] The counter output turns off when the current counter value becomes smaller than the on-preset value. The interrupt process (INT2n) starts up if an interrupt program is used in the running user program.

6] The counter values wrap around in a ring. That is, the current counter value becomes FFFFH when one more pulse is counted after the minimum value (0H) is reached. Note also that the initial value of the counter is 0H, and the value reaches FFFFH after the first pulse is counted after the start of operation.

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