LT DIN Rail Digital Transmitter with Serial Data Communication and Analog Outputs for Time of Periodic Event Applications P/N LT61FR

Time of Periodic Event Transmitter Frequently Asked Questions

What's the practical difference between this transmitter and the single/accumulated event stopwatch version?

This transmitter is built around averaging multiple periodic intervals over a selectable gate time to produce a stable representative reading of a repeating signal, while the single/accumulated event version times one discrete start-to-stop event and separately tracks an accumulated running total — different use cases depending on whether the signal is a one-off event or a continuously repeating pulse train.

Why does resolution improve as the measured interval gets shorter?

The documented resolution table ties finer resolution to smaller measured ranges — down to 0.2 µs within the 0-0.099999 second range — because averaging multiple short cycles within a fixed gate time allows the transmitter to resolve much finer timing detail than a single measurement of the same short interval could achieve alone.

How does gate time selection affect the averaged reading?

A longer gate time incorporates more individual cycles into each average, producing a more stable reading at the cost of a slower update rate, while a shorter gate time updates faster but averages fewer cycles together, potentially showing more cycle-to-cycle variation in the output.

When would I use time delay mode (A to B) versus tying A and B together for pulse width?

Time delay mode is used when the start and stop events come from genuinely separate channels or sensors, useful for measuring the interval between two distinct periodic signals. Tying A and B together instead measures the width of a single repeating pulse directly, since the same waveform's own rising and falling edges become the start and stop triggers.

Can this transmitter's start/stop triggers come from another instrument's relay outputs?

Yes — a separate Laureate meter, counter, or transmitter with relay outputs can generate the timing pulses, such as switching a relay when a monitored value like temperature crosses a setpoint; that relay switching event becomes the pulse edge this transmitter uses, letting it time recurring process behavior tied to conditions elsewhere in the system.

Why would I choose this over a bench oscilloscope for characterizing a periodic signal?

An oscilloscope suits one-off lab viewing and timing, but a fixed installation needing ongoing digital timing accuracy plus control outputs (relays reacting to the measured average) is documented as better served by a dedicated timer transmitter, which is the lower-cost choice for that specific combination of needs.

What does the pulsed laser application actually measure with this transmitter?

It's documented as capturing averaged elapsed time, pulse width, pulse separation, duty cycle, and repetition rate from a repeating pulse train — a broader characterization of the pulse train's overall behavior rather than a single pulse's individual characteristics.

Can I use this transmitter to time an isolated, non-repeating event instead of a periodic one?

While it can technically time a single interval, its design and averaging behavior are specifically built around repeating periodic signals; a genuinely single, non-repeating event with an accumulated running total is better matched to the dedicated single/accumulated event stopwatch transmitter instead.

What input types can generate the periodic pulses this transmitter measures?

The dual-channel signal conditioner accepts AC signals, and pulses from NPN or PNP transistors, contact closures, and magnetic pickups, so the periodic signal can originate from a wide range of sensor and switching types without needing separate signal conditioning.

Can multiple periodic-event timer 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.

Time of Periodic Event Transmitter Questions From the Field

My averaged reading seems to lag behind real changes in the process — what should I check?

A longer gate time inherently trades responsiveness for stability, since it averages more cycles into each output update; if the application needs faster response to genuine changes, reducing the gate time toward its minimum is the standard adjustment, accepting somewhat more cycle-to-cycle variation in exchange.

My averaged pulse width reading seems inconsistent with a single manual measurement using a handheld meter — why?

This is often expected rather than a fault, since the transmitter's averaged reading reflects multiple cycles over the gate time while a single handheld measurement only captures one instance; if individual cycles genuinely vary, the average and any single manual reading won't necessarily match exactly.

My time delay measurement (A to B) doesn't match what I expect from the signal — what should I check?

Verifying the edge polarity configuration (positive or negative) selected for each channel matches the actual signal shape is the first step, since selecting the wrong edge for either channel would measure the delay to or from the wrong transition point on the waveform.

My reading is unstable even with a long gate time selected — what else should I check?

If instability persists despite substantial averaging, the underlying signal itself may have genuinely high cycle-to-cycle variation rather than the averaging being insufficient; checking the raw signal's consistency independently (with an oscilloscope, if available) helps distinguish a genuinely variable process from a transmitter configuration issue.

My relay-generated start/stop pulses (from another instrument) don't reliably trigger this transmitter for periodic timing — what should I check?

Verifying the relay's switching characteristics 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 type and the timer's input configuration can cause missed or inconsistent triggers across repeated cycles.

Can electrical noise affect an averaged periodic measurement the same way it affects a single-event measurement?

Yes — noise misread as a genuine pulse edge on any individual cycle will be incorporated into the average along with legitimate cycles, potentially skewing the averaged result; checking cable shielding, grounding, and appropriate noise filter and contact debounce settings is the standard remedy.

My reading shows good resolution at short intervals but coarser resolution when the signal period increases — is that expected?

Yes — the documented resolution table specifically ties finer resolution to shorter measured ranges, so a signal with a longer period will be measured at correspondingly coarser resolution; this is a documented characteristic of the measurement range rather than a fault.