LT DIN Rail Digital Transmitter with Serial Data Communication and Analog outputs for Time of Single or Accumulated Event Applications

Time of Single or Accumulated Event Transmitter Frequently Asked Questions

What's the difference between the A-A, A-B, and tied A/B timing modes?

A-A mode times between two edges on the same channel (useful when a single sensor produces both the start and stop trigger). A-B mode uses independent edges on two separate channels, allowing the start and stop to come from different sensors entirely. Tying A and B together specifically measures the width of a single pulse, since the pulse's own rising and falling edges become the start and stop triggers.

Why does the transmitter track both a single event time and an accumulated time simultaneously?

These serve different questions — Item #1 (single event) answers "how long did this particular occurrence take," resetting with each new start pulse, while Item #2 (accumulated) answers "how much total time have all occurrences taken so far," which is useful for applications like tracking total machine uptime rather than just the duration of the current cycle.

How can another instrument's relay outputs generate the start and stop pulses for this transmitter?

A separate Laureate meter, counter, or transmitter with relay outputs can be configured to switch its relay when a monitored value (like temperature) crosses a setpoint; that relay switching event becomes the pulse edge this timer transmitter uses as its start or stop trigger, allowing the timer to measure durations tied to conditions in another part of the system.

Why would I use this transmitter instead of an oscilloscope for pulse timing?

An oscilloscope is well suited to viewing and timing pulses in a lab setting, but a fixed installation that needs ongoing digital timing accuracy plus control outputs (like relays reacting to the measured time) is better served by a dedicated timer transmitter, which is documented as the lower-cost choice for that specific combination of needs.

What does 0.2 µs resolution actually enable?

It allows the transmitter to time very brief events accurately, such as narrow pulse widths in a pulsed laser system or other fast-switching signals, where coarser timing resolution would either fail to register the event accurately or introduce significant relative error into a short duration.

Can this transmitter measure duty cycle directly?

Duty cycle is documented as one of several pulsed-signal characteristics (alongside pulse width, separation, and repetition rate) that dual-channel counters and transmitters in this family can capture; the specific combination of measurements needed determines how the channels and timing modes are configured.

Why does timing resolution vary depending on the interval being measured (0.2 µs to 1 hour)?

The transmitter's internal clock counting and display formatting adjust based on the magnitude of the interval being timed, so a very short event gets fine microsecond-level resolution while a very long event (up toward 999,999 hours) is tracked at a coarser resolution appropriate to that timescale.

What input types can trigger the start and stop pulses?

The dual-channel signal conditioner accepts NPN or PNP proximity switch outputs, TTL or CMOS logic, magnetic pickups, contact closures, and voltage signals from 12 mV to 250 Vac, so the start and stop triggers can come from a wide range of sensor types without needing separate signal conditioning.

Can multiple stopwatch transmitters be networked together?

Yes — up to 30 LT Transmitters and/or Digital Panel Meters can be daisy-chained on RS485 for LAN integration, or a high-speed Ethernet or WiFi communication board can be used instead for network connectivity.

Does contact debounce affect timing accuracy when using a mechanical switch as a trigger?

Yes — a mechanical switch or relay contact can produce multiple rapid transitions during a single physical actuation, and without adequate debounce filtering (0, 3, or 50 ms selectable), the transmitter could register a spurious extra start or stop pulse from that bounce rather than the single intended trigger; selecting an appropriate debounce setting for a mechanical contact source is the standard practice.

Time of Single or Accumulated Event Transmitter Questions From the Field

My timed interval seems to reset unexpectedly before the actual event ends — what should I check?

Confirming the transmitter isn't seeing an unintended additional start pulse mid-event — from noise, a bouncing contact, or an unrelated signal on the trigger channel — is the first step, since a new start pulse resets the current single-event timing to zero by design.

My pulse width measurement (A tied to B) doesn't match what I expect from the actual signal — why?

Verifying the edge polarity configuration (positive-to-negative vs. negative-to-positive) matches the actual shape of the pulse being measured is the first step, since selecting the wrong edge combination for a given pulse polarity would produce a width reading based on the wrong portion of the waveform.

My accumulated time total doesn't match what I calculate by adding up individual event durations manually — what's the likely cause?

Confirming the transmitter is actually configured to track accumulated time (Item #2) rather than only displaying the current single-event time (Item #1) is the first step, since a unit not tracking accumulation wouldn't show a running total that matches a manual sum of individual events.

My start/stop pulses generated from another instrument's relay don't reliably trigger this transmitter — what should I check?

Verifying the relay's switching characteristics (contact type, response time, and signal level) are compatible with what this transmitter's input is configured to detect is the standard first step, since a mismatch between the relay's output characteristics and the timer's input configuration can cause missed or delayed triggers.

My timing measurement seems noisy or inconsistent for very short pulse widths — what should I check?

Very short intervals are more sensitive to any noise or jitter on the trigger signal itself, since a small timing error represents a larger relative error on a short duration; checking cable shielding, grounding, and signal quality on the trigger channels is the standard first step for noisy short-interval readings.

My displayed time format doesn't match what I expect (decimal vs. clock format) — how do I change it?

The transmitter supports both a 6-digit decimal H, M, or S format with a decimal point and an HH.MM.SS clock format; confirming which format is selected in the setup software and switching to the intended one resolves a display that looks correct numerically but in the wrong format.

Can electrical noise on the trigger channels cause spurious start or stop events?

Yes — noise misinterpreted as a genuine pulse edge can trigger an unintended start or stop; checking cable shielding, grounding, and the selected noise filter and contact debounce settings is the standard remedy for suspected false triggering.

My single-event timer shows a plausible but slightly different reading each time for what should be an identical repeated event — is that expected?

Small run-to-run variation is normal for a mechanical or process-driven event, since the physical trigger points themselves (a switch actuation, a relay setpoint crossing) rarely occur at exactly identical instants each cycle; if the variation is larger than expected, checking whether the trigger source itself is producing consistent, clean edges is a more likely explanation than a timing fault in the transmitter.