Timer Control Instructions - Hitachi NT2021XA Instruction Manual

2.5

Timer Control Instructions

The easy sequence function of the inverter has a timer function that can be used in the following two modes:
(1) Free-running timer mode
(2) Timer contact output mode (timer-start, timer-stop, and delay operations)
The timer function uses eight timer counter circuits that are configured as shown in the figure below.
<variable> or
<constant>
timer stop
instruction
timer set
instruction
delay on/delay
off instruction
Counting
cycle
(10 ms)
TC (k): Timer counter variable (up counter)
TD (k): Timer contact (one-shot timer)
The timer counter is a 31-bit up counter that runs in a 10-ms cycle (1 count per 10 ms), and operates as a free-running timer when the
execution of a easy sequence program is started.
When the timer set, delay on, or delay off instruction is executed, the timer counter is cleared and restarted. While the timer counter is
operating, its count is compared with the count specified by a variable or constant to determine whether they match. When the counts
match each other, the timer counter stops counting.
When the timer off instruction is executed, the timer counter is cleared and restarted. Subsequently, the timer counter operates as a
free-running timer.
The
TC (0)
counter
starts.
Comparison
for matching
TD (0)
Y (00)
[PRN]
32 32
Comparison for
matching
CLR
Block diagram for timer function
2^31-1
delay on Y (00) TD (0) 1000
Example of timer function operation
Timer buffer (count)
32
32
Up counter
UP
(counting cycle:
10 ms)
1000
delay off Y (00) TD (0) 1500
2-23
Chapter 2 Syntax
In timer contact output mode
1
TD (k)
S Q
Latch
R
CLR
In free-running timer mode
32
TC (k)
2^31-1
1500
timer off TD (0)