Make CLICK drum step times editable from an HMI panel

Why can't you edit a CLICK drum step time from the panel?

Because in time-base mode the step durations are part of the Drum instruction's configuration, not values in memory. A panel numeric entry can only write registers, so every timing change means opening the project and rewriting the PLC.

The drum is a sequencer: it walks a fixed list of steps and switches outputs on and off at each one. On the time base, every duration is typed into the drum when it is programmed, the same way a constant belongs to a rung. There is no register behind those numbers, so the panel has no address to target. Sequencer instructions in other PLC families draw the same line between configured parameters and editable data; the page listing SQL versus SQO instruction parameters that cannot be changed shows the split for one such pair. The practical cost shows up on the floor: trimming a dwell time becomes a laptop job with a project edit and a download, which is exactly what the panel was supposed to remove.

How does event-base mode make the step times editable?

The drum's configuration has two radio buttons in its upper left corner, one for time base and one for event base. Event base lets each step advance on a configured event such as a timer's done contact.

That is the opening the editable times need. Run each adjustable step on its own timer, and let the timer's done contact be the event that ends the step: the drum enters step N, a rung enables timer N, the timer counts up to the preset, and the done bit advances the drum. Enter the timer's preset as a DS data register instead of a typed constant. From then on, the value the timer counts to is whatever sits in that register, and a write from the panel is a new step time. The drum keeps doing the sequencing and the output switching exactly as before; only the way a step ends moves from the clock to a timer you own.

What do you need before you change the program?

Collect four things: the CLICK project with the drum, one spare DS data register for every adjustable step, one numeric entry object on the panel for each of those registers, and a panel-to-PLC write path you have already checked on a spare register.

• The project and a way to write it. The programming software on a laptop, the current project file, and the cable or network path you use for downloads.
• A register plan. List the steps worth tuning, assign each its own DS register, and name it after the step. Check nothing else in the ladder writes that register; two users of one register is how an unrelated timer starts drifting.
• Panel objects. One numeric entry per register, with minimum and maximum limits set to the slowest and fastest the machine tolerates.
• A mapped write path. If the panel reaches the CLICK through a Modbus map instead of native addresses, settle that table first; the article on mapping CLICK PLC addresses to Modbus for an HMI panel walks it.

How do you switch the drum to event base and wire in the timers?

Open the Drum instruction, select the event-base radio button in the upper left, and give every adjustable step the same event chain: a timer rung that runs only during that step, with the step's DS register as the preset and the timer's done contact as the event.

1. Open the drum's configuration and switch the upper-left radio button from time base to event base.
2. Set each step's advance condition. For a timed step, the condition is the done bit of that step's own timer.
3. Add one timer rung per adjustable step. Make it true only while the drum is in that step, so the timer starts when the step starts and resets when the drum moves on.
4. Enter each timer's preset as its DS register, not a typed constant.
5. Leave steps whose timing never changes on a typed constant preset; only steps operators will actually tune need a register.
6. Write the project to the PLC, and keep the pre-change project file as your way back.

How do you point the panel's numeric entries at the DS presets?

In the panel project, add one numeric entry object per adjustable step. Aim it at that step's DS register, set entry limits to the range the machine tolerates, and label the field with the step name and its unit.

1. Put the DS address into the object's PLC address field and give it read and write on that one register, the same one-object-one-address pattern as an HMI pot that reads and writes a PLC memory value.
2. Set the minimum and maximum entry limits so a typo cannot ask the machine for a 0.5 s clamp or a 300 s dwell.
3. Decide the unit on the label. An entry of 40 means 4.0 s if the timer's increment is 0.1 s and 40 s if it is 1 s. Print the increment on the screen or scale seconds to counts in the object.
4. Add a numeric display on each timer's accumulated value next to the entry, so the crew can see a step counting down to its preset.

Will the edited step times survive a power cut?

Only where the preset registers sit in retentive memory, and the margin is thin: CLICK CPUs with an Ethernet port and CLICK PLUS CPUs hold retentive data for about one hour without a battery, so an overnight outage can erase unsaved edits.

So mark the preset registers retentive in the project's memory configuration. Find out whether the CPU has a battery fitted before anyone relies on edits across a shutdown; the one-hour figure applies with no battery fitted. On a line that starts cold after a long stop, the sturdier habit is to reseed the registers from a saved set of values at startup, either from the panel or from a first-scan rung, so the sequence never restarts on stale timing.

What does a three-step example look like with real numbers?

A press sequence clamps for 5.0 s, dwells for 12.0 s and ejects for 3.0 s, and with the step timers set so one count is 0.1 s the DS presets come out at 50, 120 and 30 counts.

The arithmetic is one line per step: preset counts equal the step time divided by the increment.

The full cycle runs 5.0 + 12.0 + 3.0 = 20.0 s. When the process engineer asks for a faster dwell, the panel edit is one write: 8.0 ÷ 0.1 = 80 counts into step 2's register, and the cycle drops to 5.0 + 8.0 + 3.0 = 16.0 s, with no laptop and no download. The 0.1 s increment belongs to this example's timers. Recompute the counts for whatever increment your timers use and carry the conversion onto the panel label.

How do you check the edits before operators get the panel?

Verify the whole chain on one step first: enter a test value at the panel, confirm the DS register changes in the PLC's data view, then time that step with a stopwatch against the number you entered.

• Enter 7.5 s at the panel. With the example's 0.1 s increment that is 7.5 ÷ 0.1 = 75 counts in the register; open the data view and confirm the 75 is there.
• Edit only step 2's register, then re-read step 1's register and confirm the first value is untouched; that catches one address written from two places.
• Run three cycles and time the edited step on each pass; all three should land at the entered time give or take a count.
• If the entry never lands in the register while other panel objects write fine, the tag-versus-address problem has its own diagnosis in the article on fixing an HMI tag that ignores PLC register writes.

Run the first timed cycles with the guards closed and nobody inside the machine envelope, because an edit that shortens a step releases the next motion sooner than the crew expects.

When is the pointer COPY table worth the extra work?

Keep one DS preset per step for sequences up to about a dozen timed steps. Reach for a COPY instruction driven by a pointer only when the step list is long; the CLICK help topic CL195 documents how COPY uses pointers.

The table arrangement holds every step's value in one block of data memory, with the pointer selecting the active step's entry and the ladder copying it into the timer data. It packs a long sequence into little ladder, but the copied value works as an accumulator preload, so until the per-step conversion is worked out the timing comes out reversed: a step ends early, runs long, or appears to run backwards. Derive the conversion for your timer's increment. Keep the operator-facing seconds separate from the preload value in the labels, and stopwatch every step before production. For the layout, the article on storing HMI step times and output bitmaps in one PLC table shows the pattern.

Recommendation: run the event-based drum with one DS register per adjustable step for short and mid-size sequences. It is one timer rung per step, the panel's writes land directly in the presets the timers actually use, and every entry reads as seconds, so there is no preload arithmetic to defend. Reserve the pointer COPY table for long step lists, and only after each step's preload conversion has passed the stopwatch test.

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