Hitachi NJI-350B manual UP/DOWN Counter

OUT CTU n s OUT CTD n

Chapter 5 Instruction Specifications

Item number

Basic instructions-25, 26

Name

Up (CTU n) and down (CTD n) of up/down counter

(UP/DOWN COUNTER)

Ladder format

Condition code

Processing time (∝s)

Remark

CTU n s

R7F4

R7F3

R7F2

R7F1

R7F0

Average

Maximum

CTD n

DER

ERR

SD

V

C

Upper case: CTU

z

z

z

z

z

1.4



Lower case: CTD

Instruction format

Number of steps

OUT CTU n s

Condition

Steps

OUT CTD n

CTU

5

1.4



CTD

3

Bit

Word

Double word

Constant

Usable I/O

X

Y

M

CU, CT

WX

WY

WM

TC

DX

DY

DM

Other

R,

TD, SS,

WR,

DR,

n

Counter number

{

0 to 255 (Decimal)

s

Set value

{

{

{

{

1 to 65535 (Decimal)

Function

•For the UP counter, increments the progress value by 1 each time the leading edge of the startup condition is detected, while it decrements the progress value by 1 for the DOWN counter. The coil switches on when the progress value is greater than or equal to the set value and switches off when the progress value is less than the set value. When the counter clear CL n switches on, the progress value is cleared to 0 and the coil switches off.

•The progress value is set in TC n, and the value will be in the range of 0 to 65535 (decimal).

•If the progress value is updated during RUN, the operation will be performed using the new progress value at that point.

•If an I/O is set for the set value, the set value can be changed during operation by changing the I/O value, since the set values are updated during each scan.

Notes

•A maximum of 256 points can be used for the timers and counters TD, SS, CU, CTU and CTD in total.

•The timer numbers and counter numbers cannot be overlapped.

•The numbers for the UP coil and DOWN coil must be the same.

•While the counter clear CL n is on, the rise of startup condition is ignored.

•Since the startup condition of the counter is edge detection, the condition for one scan may not be detected during the first scan after RUN starts.

•If the set value is set to “0”, it is regarded as a coil that is always on and controlled by the CL n.

5-34