Drum Instruction
Programming
6–13
Drum Instruction Programming
Drum instructions use four counters in the CPU. The ladder program can read the
counter values for the drum’s status. The ladder program may write a new preset
step number to CT(n+2) at any time. However, the other counters are for monitoring
purposes only.
Counter Number Ranges of (n) Function Counter Bit Function
CT(n) 0 – 174 Counts in step CTn = Drum Complete
CT( n+1) 1 – 175 Timer value CT(n+1) = (not used)
CT( n+2) 2 –176 Preset Step CT(n+2) = (not used)
CT( n+3) 3 –177 Current Step CT(n+3) = (not used)
The following ladder program shows the DRUM instruction in a typical ladder
program, as shown by DirectSOFT. Steps 1 through 10 are used, and twelve of the
sixteen output points are used. The preset step is step 1. The timebase runs at (K10
x 0.01) = 0.1 second per count. Therefore, the duration of step 1 is (25 x 0.1) = 2.5
seconds. In the last rung, the Drum Complete bit (CT0) turns on output Y0 upon
completion of the last step (step 10). A drum reset also resets CT0.
1 K0025
DRUM CT 0
Step Preset: K 1
0.01 sec/Count: K 10
Step # Counts
2 K0020
3 K1500
4 K0045
5 K0180
6 K0923
7 K1200
8 K8643
9 K1200
10 K4000
11
12
13
14
15
16
Start
Reset
ffffFffFFffFfffF
ffffFfFffFffffFf
fffffFfFfFffFffF
ffffffFfFffFffFf
ffffFfFfFfFfffFf
fffffFffFfFfffFF
fffffFfffFfffFff
ffffFffFffFffFfF
ffffFFFFFFFFFFFF
fffffFfFfFfFfFff
ffffffffffffffff
ffffffffffffffff
ffffffffffffffff
ffffffffffffffff
ffffffffffffffff
ffffffffffffffff
( ) ( ) (C30) (Y20) (C2) (Y6) (Y42) (C10)
( ) ( ) (C14) (Y10) (C4) (Y5) (Y13) (C7)
DirectSOFT Display
X0
X1
Drum Complete
CT0
Y0
OUT
15 0
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