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The time base can be selected between 10 mS, 100 mS, and 1S
for each mode of functioning.
The current value of the timer is a multiple of the selected time
base. For example, a current value of 50 in a timer with a base
time of 10 mS corresponds to 500 mS, and with a base time of 1 S
corresponds to 50 S.
The preset timer (PT) value can be a constant, or the contents of
an area VW, SMW, AI, or TR.
7.5 Counters C
The TD320 has 64 counters of 16 bits. These are available in two
modes of functioning:
•
MUP forward counter
: the counter bit (contact C) is activated
when the current value (word C) is greater than or equal to the
pre-established value (PV). The counts increments each time
the input of the up-count Cx(UP) is active and decrements
each time the input of the down-count Cx(DOWN) is active.
The counter will be set to zero upon activation of the reset
input Cx(RESET) or when the operation MOV(Cx=#0) is
executed. Upon reaching the maximum value (32767), the rise
of the next up-count will leave the current value unchanged.
Similarly, upon reaching the minimum value (-32768) the rise
of the next down-count will leave the current value unchanged.
For the forward counters, the pre-established value (PV) is
compared with the current value at the end of each cycle of
the program. If the value is greater than or equal to the preset
value, the counter bit activates (counter C), otherwise it is
deactivated.
•
MDOWN backward counter
: the counter bit (contact C) is
activated when the current value (word C) becomes equal to
zero. The counter decrements from a pre-established value
(PV) on the rise of the input of down-count Cx(DOWN) and
increments on the rise of the input of up-count Cx(UP). Upon
reaching the maximum value (32767), the rise of the next up-
count will leave the current value unchanged. The counter
resets the count bit (contact C) and loads the preset value
