Automationdirect.com DL05 - Step Transitions; Drum Instruction Types; Timer-Only Transitions

Drum Instruction
Programming
6–4
Drum Instruction Programming
Step Transitions
There are two types of Drum instructions in the DL05 CPU:
S Timed Drum with Discrete Outputs (DRUM)
S Time and Event Drum with Discrete Outputs (EDRUM)
The two drum instructions include time-based step transitions, and the EDRUM
includes event-based transitions as well. Each drum has 16 steps, and each step
has 16 outputs. Refer to the figure below. Each output can be either an X, Y, or C coil,
offering programming flexibility. We assign Step 1 an arbitrary unique output pattern
(
f= Off, F= On) as shown. When programming a drum instruction, you also
determine both the output assignment and the On/Off state (pattern) at that time. All
steps use the same output assignment, but each step may have its own unique
output pattern.
Drums move from one step to another based on time and/or an external event
(input). Each step has its own transition condition which you assign during the drum
instruction entry. The figure below shows how timer-only transitions work.
F
f
ff
F
f
F
ffff
FF
fff
Step 1 Outputs:
ff
f
F
ffff
FF
f
F
ff
FF
Step 2 Outputs:
Has counts per
step expired?
No
Yes
Increment
count timer
Use next transition criteria
The drum stays in Step 1 for a specific duration (user-programmable). The timebase
of the timer is programmable, from 0.01 seconds to 99.99 seconds. This establishes
the resolution, or the duration of each “tick of the clock”. Each step uses the same
timebase, but has its own unique counts per step, which you program. When the
counts for Step 1 have expired, then the drum moves to Step 2. The outputs change
immediately to match the new pattern for Step 2.
The drum spends a specific amount of time in each step, given by the formula:
Time in step = 0.01 seconds X Timebase x Counts per step
Drum Instruction
Types
Timer-Only
Transitions