Self-Resetting Drum; Initializing Drum Outputs; Using Complex Event Step Transitions - Automation Direct DL05 User Manual

In the figure below, we focus on how the Jog input works on event drums. To the left of the
diagram, note that the off-to-on transitions of the Jog input increments the step. Start may be
either on or off (however, Reset must be off ). Two jogs takes the drum to step three. Next, the
Start input turns on, and the drum begins running normally. During step 6 another Jog input
signal occurs. This increments the drum to step 7, setting the timer to 0. The drum begins
running immediately in step 7, because Start is already on. The drum advances to step 8
normally.
As the drum enters step 14, the Start input turns off. Two more Jog signals moves the drum
to step 16. However, note that a third Jog signal is required to move the drum through step
16 to "drum complete". Finally, a Reset input signal arrives which forces the drum into the
preset step and turns off the drum complete bit.
Inputs
S tart
Jog
R es et
Drum S tatus
S tep #
Drum
Complete (CT0)

Self-Resetting Drum

Applications often require drums that automatically start
over once they complete a cycle. This is easily
accomplished, using the drum complete bit. In the figure
to the right, the drum instruction setup is for CT0, so we
logically OR the drum complete bit (CT0) with the Reset
input. When the last step is done, the drum turns on CT0
which resets itself to the preset step, also resetting CT0.
Contact X2 still works as a manual reset.

Initializing Drum Outputs

The outputs of a drum are enabled any time the CPU is in run mode. On program-to-run
mode transitions, the drum goes to the preset step, and the outputs energize according to the
pattern of that step. If your application requires all outputs to be off at powerup, make the
preset step in the drum a "reset step", with all outputs off.

Using Complex Event Step Transitions

Each event-based transition accepts only one contact reference for the event. However, this
does not limit events to just one contact. Just use a control relay contact such as C0 for the
step transition event. Elsewhere in ladder logic, you may use C0 as an output coil, making it
dependent on many other "events" (contacts).
Chapter 6: Drum Instruction Programming
Jog
drum drum
1
0
1
0
1
0
1 2 3 3 3 4 5
1
0
DL05 Micro PLC User Manual, 6th Edition, Rev. A
Drum
Completed
Jog Jog
drum
6,7 8 ... 14 15 16 16
X0 X0 Start
Setup
Jog
X1 X1
Info
X2 X2 Reset
CT0 Steps
1
2
3
4
5
6
R es et
drum
7
8
9
16 1
10
11
Outputs
12
13
f f f f F f
F F f F f
F
14
f f F F
F f
A
B
C
D
6–11