Every HMI timer object needs the PLC memory address behind the timer instruction: the V-memory word that holds the current value and the register that supplies the preset. Find both in the ladder software and the CPU manual, test one timer online in a safe machine state, then copy the two objects to the remaining timers and verify each address.
An HMI numeric object reads and writes one memory address. It has no view of the ladder rung, so linking a timer to the panel means finding the two addresses behind each timer instruction: the word that holds the running count and the register that supplies the preset. Map both for every timer on the screen, test one timer end to end online, then copy the objects to the rest.
What you need
- The PLC project open in the programming software, with online access for the test
- The panel project open in the HMI configuration software, with the driver for your PLC selected and communicating
- The CPU manual for the PLC. Its specifications chapter documents where timer values live; for this PLC family the timer current values are stored in V-memory, and the chapter's V-memory location table gives the word for each timer number
- A record sheet with one row per timer: timer number, preset source address, current-value address, time base and valid range
The panel software reads and writes the address configured on each object, and the meaning of the value comes from that address. Write the mapping down before any screen object is built.
Find each timer's two addresses
Every timer you put on the screen has two values and they live in different places. The current value is the live count while the timer runs. The preset is the duration the timer is set to reach.
The PLC manual documents the first address: timer current values are stored in V-memory. Look up each timer number in the manual's V-memory location table and write the word on the record sheet.
The second address comes from the rung. Open each timer instruction in the ladder software and read its preset operand. If the operand is a register, that register is the address the entry object must write. If the operand is a constant, the preset is hard-coded and no panel entry can change it until the program moves the value into a register the rung uses; that pattern is walked through in changing a PLC timer constant preset from an HMI panel.
Note the time base in the same pass through the rungs. Compact PLC timers count in fixed steps and a 0.1 s step is common; the timer documentation for your model prints the step it uses, and the panel's number format has to show the same units.
| Record for each timer | Where the value comes from |
|---|---|
| Preset source address | The preset operand on the timer rung |
| Current-value address | The CPU manual's V-memory location table |
| Time base and range | The timer instruction and the program's accepted range |
Build one display and one entry per timer
Each timer gets two objects, pointed at two different addresses:
- A numeric display object on the current-value address, which shows the live count while the timer runs.
- A numeric entry object on the preset source address. This is the only object an operator uses to change the timing.
Set the number format on both to match the PLC: digit count, decimal places, any scaling. With a 0.1 s time base, one decimal place turns 50 counts into 5.0 s on screen. Set the entry limits to the program's accepted range and keep a clamp rung in the ladder as the second guard, as shown in clamping HMI numeric entry limits in PLC ladder logic.
Label every object with the timer's purpose and its units, and keep each preset entry visually separate from its live display. Labels matter more when the panel is one of several shop-floor screens and andon boards on the same line, where any operator may step up to any screen.
If a display stays at zero or never moves after download, check the object's tag address first; the numeric display that shows nothing walks through that check.
Example: seven timers on one screen
Say the program has seven timers, numbered 1 through 7, each counting at a 0.1 s time base. In this example the manual's V-memory table lists one word per timer in timer-number order, so timer 1's current value sits in the first word of the timer area and timer 7's in the seventh. Read your own table line by line: the order it prints is the order that goes on the record sheet.
Each editable preset needs its own word, seven more for seven register-sourced presets. The mapping is 7 current-value addresses plus 7 preset addresses, and the finished screen carries 14 objects: 7 displays and 7 entries.
Suppose the operators need a 5.0 s delay on timer 1. In counts: 5.0 s ÷ 0.1 s per count = 50 counts. Set that timer's entry limits to 0 through 600 counts, which is 60.0 s at the same time base. When someone types 50 into the entry, the panel writes 50 into timer 1's preset word, and the display object on the current-value address counts up in the same units and reads 5.0 when the current value reaches 50.
Test one timer online, then copy the screen
- Bring the machine to a safe, non-production state first. A mistyped address writes into whatever word the digits name, and that word may control something that moves.
- Download the panel project and open the ladder software online beside it.
- Run timer 1 and watch its current-value word in the ladder software. The panel display on that address should show the same number climbing. A disagreement means the display object sits on the wrong word.
- Type 50 into the entry and confirm two things online: timer 1's preset word now reads 50, and the timer times out at 5.0 s. If the panel accepts the value but the word snaps back, another rung writes that word; find that instruction and resolve it before any copying.
- Copy the two objects to the other six positions and change only the address and the label on each copy. Verify the six one at a time: each entry moves its own preset word and no other timer's word changes.
The order is the same one used in testing operator panel writes before motion, whatever the screen ends up driving.
Recommendation: Source every editable preset from its own V-memory word, point the entry object at that word, and take one timer through the full online test, display and entry together, before the objects are copied. On a seven-timer screen that is one careful timer followed by six quick, verified copies.
If the timer ignores the new preset
The entry was accepted and the preset word changed, but the timer still runs to the old time. Look in two places:
- A move or calculation rung writes the preset word every scan and overwrites the operator's value. Give the operator value its own home register and load it into the preset only when it changes, or edit the writing rung.
- The word you wrote is not the operand the timer instruction reads, which happens when the rung sources its preset from a constant. Move the operator's value into the register the rung actually uses.
Both are ladder problems, and both surface in the one-timer online test long before the screen is cloned.
Questions
Can I point the panel object straight at the timer number?
Some panel drivers accept a timer-number reference in their address selection, so open the driver's address help and see what it offers. Whatever the shortcut resolves to, make it agree with the CPU manual before you trust it on a running machine: the manual's V-memory location table is the documented home of the timer current value, and the preset belongs to the register on the rung.
Does the new preset take effect on a timer that is already timing?
That depends on how the rung evaluates the timer instruction, and the panel display cannot tell you. Test it online once, in a safe state: change the preset while timer 1 is mid-count and watch whether the timeout moves. If the new value only applies on the next cycle after the rung goes false and true again, tell operators that, because it is the program's behavior and it will be the same on all seven timers.
How do I stop an operator from typing a value the line cannot run?
Two limits, in this order. Set the entry object's minimum and maximum to the range the program accepts, which stops the value at the panel before it reaches the PLC. Then keep a clamp rung in the ladder as the second guard, so a value that reaches the PLC by any other path gets clamped to the accepted range before the timer reads it. The clamp lives in the program, so it protects the timer even when a different screen or a laptop write hits the same word.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.