Timer Functions - ABB AC 31 Technical Manual

5.7. Timer functions

ABB Control - AC 31
1SBC 260400 R1001-b 06.99
Programming
Each of the following described functions is time dependent.
The temporal value is placed in an indirect constant KD or in a double word variable MD . In the
case of word arithmetic calculations or MODBUS
use, for timer functions described below, the words KW or MW instead of double words. In this
case, you should not use the word with the address KW+1 or MW+1 in the program.
The temporal values may vary from 1 ms to 596 hours and 30 minutes for a double word and
from 1 to 65 535 ms for a word type variable. The chosen values on the master central unit
should be multiples of 5 ms.
To achieve the 65 535 ms value with a word type variable you have to enter the value -1 as
shown in the graph below. By analogy, you have to enter the value (x-65536) for the time
values (x) between 32 768 and 65 535.
-32768
Value of MW/KW
32768
Time value in ms
The time unit used for the entry is in milliseconds.
The number of timers in a program is unlimited but there may not be more than 42 timers
running at the same time on the central unit.
When switching from RUN mode to STOP mode the time values of incomplete timers are not
saved. The timers are therefore reset to zero at the next passage to RUN mode.
Two cases present themselves if a timer value is modified while the timer is running:
- If the time of the new value has already been exceeded the timer stops and the new
time value is not taken into account until the next time the timer is activated.
- If the time of the new value has not yet been exceeded then the time already passed
is taken into account and the timer stops when it has attained the new value.
®
protocol communication, it is possible to
-1 0
x - 65536
x
65535
0
32767
32767
Page 5-37