[Technical tips]
Laser processing equipment — marking, cutting, drilling, trimming — commonly requires the input-to-output trigger path to respond within 100 µs. We wired up a QEC-M-02 and measured what its local isolated I/O can actually do.
The result:
QEC-M-02 local 24 V isolated I/O, DO→DI loopback (measured, ~25 °C, light load): Rising edge (0→1): 67.3 – 80.7 µs · Falling edge (1→0): 90.9 – 94.2 µs Observed timing spread (max−min): 13.4 µs (0→1) / 3.3 µs (1→0)
You can download the report here: 202512_M02_DIO_0-1_Ans_v1r1.pdf
Both edges measured under 100 µs — using nothing more than a simple sketch in the 86Duino Coding IDE and the onboard isolated I/O. No dedicated trigger hardware, no special firmware.
1. Why This Matters for Laser Machines
A typical fast loop in a laser machine: photoelectric sensor / encoder mark → DI → application logic → DO → laser gate or shutter driver. At a stage speed of 1 m/s, every 100 µs of latency is roughly 100 µm of travel — and any variation in that latency becomes placement error you cannot calibrate out.
With remote fieldbus I/O, this loop has to ride the bus cycle in both directions. In a conventional cyclic configuration (250 µs – 1 ms update), the full input–logic–output round trip typically lands well beyond a 100 µs target — not because of any protocol limit, but simply because the path crosses the bus twice. EtherCAT remains the right backbone for synchronized motion and distributed I/O; the QEC-M-02’s approach is to keep the one loop that can’t wait for a cycle local: its 16 DI / 16 DO isolated channels are driven directly by the Vortex86EX2 CPU, programmed the same way as everything else on this controller — a setup() 與 loop() in the 86Duino Coding IDE.
Sensor / Encoder Mark ──► Local DI (X00) ──► QEC-M-02 logic ──► Local DO (Y00) ──► Laser Gate QEC-M-02 ──── EtherCAT ──── Servo Drives ──── Stage / Feeding Axis
One controller, both roles — no separate high-speed trigger box. (The measurements in this article characterize the local I/O path itself; see Section 3 for verifying the timing under your own application workload.)
2. How We Measured It
We looped the local DO (Y00) back to the local DI (X00) on the 24 V field side, so one measurement covers the complete path: DO switching + wiring + DI threshold crossing + software detection. Timing uses the CPU time-stamp counter (1 tick ≈ 1.875 ns at 533 MHz), cross-checked with a Tektronix TDS2012C oscilloscope.
Simplified timing-loop excerpt (benchmark use only — a production version should add a timeout and restore interrupts on every exit path):
io_DisableINT(); // suppress software jitter uint64_t t0 = timer_GetClocks64(); writeDO(Y00, HIGH); // 0 -> 1 rising edge while (readDI(X00) == 0); // busy-wait for loopback uint64_t t1 = timer_GetClocks64(); io_EnableINT(); double delay_us = (double)(t1 - t0) / 533.0;
| Transition | Minimum | Maximum | Observed spread |
|---|---|---|---|
| 0→1 (rising) | 67.3 µs | 80.7 µs | 13.4 µs |
| 1→0 (falling) | 90.9 µs | 94.2 µs | 3.3 µs |
2.1 About the datasheet numbers
The QEC-M-02 datasheet specifies the digital output at turn-on 0.25 ms / turn-off 20 µs, rated at the full 500 mA load. The measurements above were taken at light load — the DO driving only the DI input, a few tens of mA, which is also the typical condition when driving a laser controller’s logic-level gate input. PhotoMOS output stages switch on much faster at light loads (and off somewhat slower), which is exactly what the measurements show. Both sets of numbers are correct for their conditions: the datasheet remains the guaranteed specification; the values in this article are measured behavior under the stated test conditions. If response time is critical in your design, keep the DO load light — and buffer heavy loads instead of driving them directly.
3. Try It on Your Own Bench
The test is deliberately easy to reproduce: one jumper from Y00 to X00 on the 24 V terminal block, plus the timing loop above in the 86Duino Coding IDE. Our benchmark ran the timing loop on its own to establish a clean baseline; the same sketch runs unchanged alongside your EtherCAT network and application logic, so you can measure the distribution under your real workload — which is the number that matters for your machine. The complete test sketch is available from our team.
Note that the figures here are the controller’s share of the loop; your system total adds the sensor’s response time and the laser controller’s input stage. And one safety reminder: the standard digital output is for process triggering only — laser safety interlocks, emergency stops, and other safety-rated functions belong on certified safety devices, not on general-purpose I/O.
Want to check whether it fits your process?
聯繫我們 info@icop.com.tw for the test sketch or an evaluation unit — our FAEs regularly review sensor → DI and DO → laser-gate wiring for laser applications.
我們將持續提供穩健且創新的 EtherCAT 自動化平台，實現更智慧、更快速的整合。如有任何問題或需要支援，請透過 info@icop.com.tw、您當地的 ICOP分公司或 全球官方經銷商.