Technical equipment of TC600 PLC
77
TXV 138 08.02
CONT.0
- blocking of the counter
0 = blocking of the counter
1 = counter running
CONT.4
- resetting of the counter
Change of the bit state from 0 to 1 performs reset of the
counter and setting to zero of all bits of the STAT state word
(while in state 1, the counter is not reset). Setting of the bit to
zero is done by the user.
CONT.5
- control of the counter mode
0 = freely running counter
1 = self-filling counter with pre-selection
CONT.6
- allowing of interrupt from reaching of the maximum range
0 = interrupt prohibited
1 = interrupt allowed
CONT.7
- allowing of interrupt from reaching of the pre-selection
0 = interrupt prohibited
1 = interrupt allowed
To determine the minimum value of the counter pre-selection in the self-
filling mode and difference of values of two pre-selections following one af-
ter another of the freely running counter, the following relationship holds:
n
n
- value/difference of values of the pre-selection
f
- frequency of signal at the CLK input.
For servicing within the P44 process it holds that time of the interrupt
process must not exceed 5 ms. It is also necessary to keep in mind that
evoking of interrupt processes causes prolongation of the program cycle
time which may even lead to exceeding of the maximum allowed cycle
time.
Reading of the state word, counter value, and writing of the control word
and counter pre-selection can be performed by reading from and writing to
the counter physical address.
LD
U$3000
;reading of the STAT state word
LD
UW$3001
;reading of the counter state
WR
U$3080
;writing of the CONT control word
WR
UW$3081
;writing of the counter pre-selection
By reading from the physical address or writing to the physical address of
the counter, the corresponding change of the value in image of inputs or
outputs in the scratchpad memory does not happen!
In the case of physical reading, value in image of inputs is corrected in
the course of the cycle loop.
In the case of physical writing, it is necessary to ensure the correction in
the scratchpad by the user program otherwise in the cycle loop the counter
will be set according to the original value in image of outputs.
Counter pre-selection
Servicing within the
P44 process
Physical addressing
of the counter
The physical
address has no
automatic bond to
the scratchpad
