LOGO! 8 OBA6 Multi-Function Button: Short/Long Press Programming

1. Overview

The Siemens LOGO! 8 OBA6 generation — the third revision of the LOGO! 8 family — exposes a dedicated special function block for pushbutton decoding called the Comfort Switch (block number B011, German: Schalter (Komfort)). The block accepts a single Boolean trigger and resolves it into discrete short-press, long-press, and double-click events. With a few helper blocks you can drive two completely different load behaviors from a single dry contact, without writing custom edge-detection or timer logic.

The canonical use case that this article addresses is a "stairwell switch" pattern:

• Behavior A — short press (release inside the long-press window): the output latches; a second short press releases it.
• Behavior B — long press (hold ≥ T_long, e.g. 1.0 s): the output energizes and stays on for a fixed 5-minute off-delay, then drops out automatically.

Both behaviors share one pushbutton on one input; the LOGO! 8.3 OBA6 base module does the rest. The same pattern extends to double-click for a third behavior without changing the wiring.

This reference is built around the LOGO! 8.3 OBA6 hardware, LOGO!Soft Comfort V8.3, and the official LOGO! system manual. Where the documentation is ambiguous, the article shows the decision path instead of choosing silently.

2. Prerequisites

2.1 Hardware

Confirm that the engineering workstation can run LOGO!Soft Comfort V8.3 — Windows 10 (64-bit) or Windows 11. Older 32-bit installations of LOGO!Soft Comfort will not deploy to OBA6 hardware because the device description was reorganized at V8.2.

2.2 Software

Download the current build of LOGO!Soft Comfort from the official Siemens portal at siemens.com/logo-soft-comfort. The installer packages a Help system that contains the device-specific parameter ranges for the Comfort Switch; consult it when fine-tuning the long-press threshold. The Siemens Industry Online Support portal at support.industry.siemens.com hosts the LOGO! 8.3 system manual and the LOGO! application examples library, which includes a multi-function-button program that is functionally equivalent to the one built here.

2.3 Wiring topology

A single momentary N/O pushbutton lands on digital input I1. The LOGO! output Q1 drives the load (lamp, contactor coil, or relay). The schematic is identical across the relay and transistor OBA6 variants; only the load-side wiring differs.

3. The Comfort Switch (B011) in Detail

3.1 Function block footprint

The exact output naming is taken from the LOGO! system manual; older LOGO!Soft Comfort builds displayed only Q1/Q2 and exposed the long-press event on Q2 in a different way. If your installed version shows a different output set, open the block's tooltip and verify the I/O labels before wiring.

3.2 Configurable parameters

3.3 Internal state machine

When TRG rises the block arms a long-press timer. If TRG falls before the timer elapses, the event is a short press and Q2 toggles. If TRG remains HIGH past T_h, the event is classified as a long press and Q3 latches. The double-click logic on Q4 is independent and is typically left unused for a two-behavior button, but it remains available for a future expansion (for example, adding a "reset everything" output).

4. Wiring the Pushbutton and Load

1. Landing the supply: bring +24 V (or +12 V on the 12/24 RCE variant) to one side of the pushbutton contact. On the 230 V OBA6, use the dedicated 230 V input rail; the input conditioning network is different and the same firmware handles both.
2. Signal return: connect the other side of the contact to I1 on the LOGO! base module.
3. Reference: land the supply return on the M terminal of the LOGO! (negative of the input supply). On 230 V variants the reference is the L2 (neutral) rail.
4. Output: connect Q1 to the load through the appropriate protective device — fuse or circuit breaker per the OBA6 system manual, plus an RC snubber or flyback diode on inductive loads such as contactor coils or solenoids.
5. Shielding: for runs longer than 30 m, use shielded cable with the shield landed at one end only, typically the LOGO! terminal side. Unshielded long runs in noisy panels can capacitively couple enough to register phantom long presses because the Comfort Switch is sensitive to a few milliseconds of input jitter.

5. Step-by-Step Program in LOGO!Soft Comfort V8.3

5.1 Place the blocks

1. Open LOGO!Soft Comfort and create a new project. Select the OBA6 device family from the project setup wizard.
2. Drag a Pushbutton (Comfort) block (B011) from the Special function catalog onto the workspace.
3. Drop an Off-delay block (B04) next to it for the 5-minute timer.
4. Drop a 2-input OR block (B07) to combine the two branches.
5. Place an RS (SR) flip-flop (B03) for the latching branch.
6. Connect I1 to the TRG pin of the Comfort Switch.

5.2 Wire Q2 to the latching branch

1. Connect Q2 of the Comfort Switch to the S (set) input of the RS flip-flop.
2. Use a one-shot (AND with edge detection on the rising edge of Q2) to drive the R (reset) input of the RS flip-flop. This ensures that each short press flips the state once, even if Q2 stays HIGH during the press duration.
3. Route the Q1 output of the flip-flop to the upper input of the OR block.

5.3 Wire Q3 to the timed branch

1. Connect Q3 of the Comfort Switch to the trigger input of the off-delay.
2. Double-click the off-delay block and set TH = 300 s (5 minutes). Tick the retentivity box if you want the timer to survive a power cycle.
3. Route the off-delay output to the lower input of the OR block.

5.4 Drive Q1 of the LOGO!

1. Connect the OR block output to Q1 of the LOGO! base module.
2. Run the on-screen simulation first: press F3 (or use Simulate → Run). Toggle the I1 checkbox to drive the input manually and watch the Q2/Q3 indicators on each block.
3. Download to the controller via Ethernet or USB cable. The transfer dialog reports the version mismatch (if any) and the free memory on the base module.

5.5 Configure the long-press threshold

1. Double-click the Comfort Switch block to open its properties.
2. In the Hold time field, enter 1.0 s for a 1-second long-press threshold. The increment is 0.05 s.
3. Click OK to apply and recompile.

The complete logic chain reads:

Q1 (load) =  (Q2 latched through RS)  OR  (Q3 → off-delay TH = 300 s)

5.6 Timing diagram

6. Alternative: Discrete-Block Implementation

Older LOGO! generations (OBA0 through OBA4) and any third-party controller that does not expose the Comfort Switch can deliver the same behavior from a handful of standard function blocks. The recipe below works on every LOGO! 8 firmware and is the canonical back-port of the pattern.

6.1 Functional decomposition

1. Short-press detector — edge-triggered one-shot on the rising edge of I1, gated by a window during which the input must fall before the long-press threshold elapses.
2. Long-press detector — on-delay with T = 1.0 s, followed by a one-shot on the falling edge of I1.
3. Latching — RS flip-flop set by the short-press one-shot, reset by the next short press (a single press toggles the flip-flop).
4. Auto-off — off-delay started by the long-press detector's one-shot, configured to 300 s.

6.2 Block list

This totals 7 blocks. The Comfort Switch approach uses 4. Use the discrete approach only if the project is being back-ported to pre-LOGO! 8.3 hardware or if the engineering environment lacks the special-function catalog.

7. Parameter Reference

8. Verification

8.1 Simulation checklist

1. Press and release inside 1 s: the OR output toggles to the opposite of its previous state. The on-line monitor should show the RS flip-flop output transitioning and the Q2 indicator pulsing for one cycle.
2. Hold ≥ 1 s, then release: the OR output energizes; the off-delay block counts down from 300; the OR output drops automatically at zero. Q3 should latch on the long press and stay latched until the off-delay expires.
3. Hold, then short press before 5 min elapses: the long-press branch holds the output on; the off-delay continues counting. A subsequent short press flips the RS flip-flop and the output goes off immediately if reset is wired through a one-shot. If reset is wired as a level, the output will stay on while I1 is HIGH and drop when I1 falls.

8.2 On-device verification

1. Power the LOGO! on. The display (if fitted) should read "LOGO!" and the run/stop LED should be green.
2. Press the button briefly. Listen for the output relay to click; verify the lamp energizes.
3. Press the button briefly a second time. The lamp should drop out.
4. Hold the button ≥ 1 s. The lamp should energize; release; wait 5 minutes; the lamp should drop out.
5. To shorten the verification window, temporarily set the off-delay TH to 10 s in LOGO!Soft Comfort, deploy, and re-test. Restore to 300 s after the test.
6. Confirm that pressing during the 5-minute window does not extend the timer — the off-delay is one-shot; it must reach zero and re-trigger from a new long press.

9. Troubleshooting Matrix

10. Specifications Relevant to This Application

• LOGO! 8.3 OBA6 cycle time: 0.04 ms per function block worst case; 0.6 µs minimum cycle for a small program. The Comfort Switch and the off-delay together do not push a typical cycle past 10 ms even with 200 blocks.
• Input filter: 0.5 ms default, configurable to 1.5 ms or no filtering in the LOGO!Soft Comfort input properties. Use the 1.5 ms filter for mechanical pushbuttons to suppress contact bounce.
• Output ratings (relay OBA6): 8 A continuous per relay, 200,000 cycles at full load, 500,000 cycles at half load. Refer to the OBA6 system manual, section "Relay outputs", for the derating curve above 55 °C ambient.
• Memory budget: the Comfort Switch consumes approximately 12 function-block memory units (FBMs). A small project including 4 blocks and 200 lines of ladder fits comfortably inside the 8,500 FBM budget of the OBA6.
• Ethernet / web server: OBA6 modules ship with the integrated web server enabled by default on port 80. The Comfort Switch's PAR pin can be exposed to the web server for runtime adjustment of the hold time without re-downloading the project.
• Real-time clock: the OBA6 carries a buffered real-time clock that can be used to log long-press events to the microSD card with a 1 s resolution. The clock's drift is ±2 s/day at 25 °C, so time-stamped logging is acceptable for diagnostics but not for tariff-metering applications.

11. Field Commissioning Notes

11.1 Debounce

Mechanical pushbuttons on a 24 V supply typically bounce 1–5 ms. The default LOGO! input filter (0.5 ms) is borderline; switch to 1.5 ms if you observe double-clicks in the Q2 branch or premature trips of the long-press branch.

11.2 Cable length

Cable runs longer than 30 m on the digital input should use shielded cable to keep capacitive coupling from registering phantom long presses. The OBA6 manual quotes 100 m maximum for unshielded, but the Comfort Switch is sensitive enough that 30 m of unshielded cable in a noisy panel can produce erratic behavior.

11.3 Retentivity

Decide explicitly whether the 5-minute timer should be retentive. For a stairwell or corridor light that must time out even after a power loss, mark the off-delay retentive. For a process signal that should restart counting on power-up, leave it non-retentive.

11.4 Display feedback

On the OBA6 onboard display, place a message text that shows "Light ON — 4:32 remaining" so the operator can see the off-delay counting down. The Comfort Switch's Q3 output can be tied directly to the message-text enable pin. The same message can be exposed through the integrated web server to a phone or tablet on the same network.

11.5 Safety

11.6 Commissioning sequence

1. Power the LOGO! with the load disconnected; verify the program downloads and the run LED is green.
2. Use the on-line monitor in LOGO!Soft Comfort to verify Q2 toggles and Q3 latches on a 1 s press.
3. Reconnect the load; verify the relay click and the lamp state with a meter.
4. Set the off-delay to 10 s; verify the timing; restore to 300 s.
5. Document the program on the microSD card; save the project archive to a version-controlled directory.

12. Related Siemens Resources

• Siemens LOGO! product page — overview, family comparison, current-generation ordering data.
• LOGO!Soft Comfort download — current engineering software; required version V8.3 or later for OBA6.
• Siemens Industry Online Support — system manual, application examples, and firmware notes for the LOGO! 8.3 / OBA6 generation.
• Siemens Automation portal — manuals, FAQs, and the LOGO! Application Examples library.

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