LT DIN Rail Digital Transmitters with Serial Data Communication and Analog Outputs for Time of Periodic Event Applications

Time of Periodic Events DIN Rail Transmitter Frequently Asked Questions

Why does resolution improve from 1 ms at the widest range down to 0.2 µs at the narrowest range, rather than staying constant across all ranges?

Documented resolution table specifically ties finer resolution to narrower measurement ranges — since the transmitter's internal count of 5.5 MHz clock pulses produces a fixed number of possible count values, spreading that same count resolution over a much wider maximum time range (199.999 s) necessarily yields coarser resolution than concentrating it over a much narrower range (0.099999 s), which is why the documented resolution figures scale together with the selected range.

Why does the finest documented resolution of 0.2 µs specifically require averaging, unlike the coarser resolution tiers?

Documented specification specifically notes "0.2 µs (after averaging)" only for the narrowest range, distinct from the other resolution tiers listed without that qualifier — this indicates that achieving the very finest resolution specifically depends on the documented multiple-integral-time-interval averaging process over the selected gate time, rather than being available from a single, unaveraged measurement the way the coarser resolution tiers are documented as being.

Does "Time to Zero Output" on this periodic-events transmitter serve the same function as "Time Before Zero Output" documented on other LT Series transmitters?

Both are documented with the same 10 ms to 199.99 s selectable range and appear to describe a related concept — the specific timeout duration after which the transmitter's output defaults to zero in the absence of valid signal — though this page's exact terminology is "Time to Zero Output" rather than "Time Before Zero Output"; the underlying function is consistent with the same category of timeout-to-zero behavior documented elsewhere in the LT Series.

Does tying Channels A and B together for pulse width measurement affect the transmitter's documented gate-time averaging capability?

No — documented description specifically states that for pulse width measurement (A and B tied together), "readings are averaged over a user-selectable gate time," the same underlying averaging mechanism documented for the separate time-delay measurement mode; tying the channels together changes what physical quantity is being measured, not whether gate-time averaging remains available.

Can the same physical transmitter be reconfigured between measuring time delay (A to B) and pulse width (A tied to B), or does this require different hardware?

Documented description presents both as configuration modes of the same Time Interval Mode transmitter, distinguished by whether Channels A and B are wired to separate signal sources or tied together — this is consistent with a wiring and setup configuration choice on the same physical hardware, rather than requiring separate transmitter models for time delay versus pulse width measurement.

Does averaging multiple time intervals over a longer gate time reduce genuine measurement noise, or does it also risk masking real variation between individual events?

Documented description specifically frames averaging as improving resolution (particularly enabling the finest 0.2 µs tier), which is consistent with reducing the effect of random measurement noise on the reported value — however, since the reported reading represents an average across the gate time's multiple intervals rather than any single interval, genuine event-to-event variation would similarly be smoothed into that average rather than reported individually, a general characteristic of any averaging-based measurement approach.

Does the documented ±1 ppm/°C span tempco figure apply to the time-delay reading, the pulse-width reading, or both?

Documented specification lists span tempco once under the general Pulse Input section, applying to the transmitter's underlying timing measurement as a whole, rather than listing separate tempco figures for time-delay mode versus pulse-width mode — since both modes share the same documented 5.5 MHz clock-counting mechanism, the same ±1 ppm/°C span tempco figure is consistent with applying regardless of which specific timing mode is configured.

Why does the "Instrumenting a Pulsed Laser System" application list duty cycle as one of the measurable parameters, when this page's core function is time interval rather than duty cycle measurement?

Documented description specifically lists duty cycle alongside elapsed time, pulse count, pulse width, pulse separation, and pulse repetition rate as parameters obtainable from Laureate dual-channel counters and transmitters in this application — since duty cycle is mathematically derivable from pulse width and pulse separation (both of which this time interval transmitter directly measures), documented duty cycle figures in this application context are consistent with being calculated from those two directly measured time interval quantities rather than measured as an independent parameter.

Does selecting a shorter gate time always provide a faster-updating reading, even at the cost of averaging fewer intervals?

Yes — documented specification ties output update rate directly to gate time (gate time + 30 ms + 0-2 time intervals), meaning a shorter selected gate time is consistent with a faster update rate; the documented tradeoff is that a shorter gate time also averages fewer individual time intervals together, which is the same general averaging-versus-responsiveness tradeoff documented elsewhere for gate time selection on related LT Series transmitters.

Can Time Interval Mode on this transmitter measure a time delay between two entirely unrelated periodic signals, or must A and B originate from the same underlying event source?

Documented description specifically states the mode allows "inputs from different sources" for the A-to-B time delay measurement, without requiring A and B to originate from the same underlying physical event — this is consistent with using this transmitter to measure the timing relationship between two genuinely independent periodic signals, provided both are periodic and their relative timing relationship is what's meaningful to the specific application.

Ignition Timing & Spark Pulse Interval Questions From the Field

Why is the time period between successive ignition sparks on one cylinder so much longer than the spark event itself?

Documented example specifically illustrates this with real figures — a spark event lasting around 2 ms compared to a documented 150 ms period between sparks on a single cylinder at 800 RPM in a 4-cylinder engine; the spark itself is documented as accounting for only around 2% of the actual work cycle, meaning the vast majority of the periodic interval between ignition events is not spark activity at all.

Does simply raising engine RPM during diagnostic testing change the fundamental interval being measured between spark events?

Yes — documented practice specifically describes technicians deliberately increasing engine RPM specifically to shorten the ignition cycle period, which is documented as "saturating" the waveform for better visibility on diagnostic equipment; this is a deliberate technique that directly exploits the known relationship between RPM and the inter-spark timing interval to make brief, otherwise hard-to-observe events more visible.

Why do different vehicle manufacturers require different correction factors when measuring ignition timing from a crankshaft position sensor?

Documented explanation specifically attributes this to manufacturers placing their crankshaft position reference notch (or equivalent pulse-generating feature) at different physical points relative to top dead center — this documented variation, driven partly by physical placement constraints and partly by differing engineering preferences, means a timing measurement device working across multiple engine types must document and apply a specific correction factor for each manufacturer's particular reference point placement.

Is there a documented reason ignition systems sometimes generate multiple pulses per single triggering event at low RPM, and how is this handled in timing measurement?

Yes — documented description specifically identifies that certain ignition systems generate several ignition pulses combined into a single group at low RPM to trigger one ignition process, and describes a specific retriggerable timer technique designed to suppress the extra pulses that follow the first pulse in such a group, ensuring the timing/RPM measurement circuit responds to the intended single triggering event rather than miscounting the group as multiple separate events.

Is there a documented typical accuracy figure achievable for dedicated automotive ignition timing measurement instruments?

Yes — one documented commercial ignition timing instrument specifically cites an accuracy figure of ±0.05 degrees for both steady-state and transient testing of ignition, camshaft, or injector timing, illustrating the level of precision documented as achievable and expected in dedicated automotive timing measurement equipment.

Does the correct diagnostic approach for verifying spark timing rely on absolute pulse timing alone, or does it also require comparing against a reference waveform?

Documented diagnostic guidance specifically recommends comparing a measured waveform (such as from crankshaft or camshaft position sensors) against a known-good reference waveform, typically sourced from a service manual, rather than relying solely on absolute timing values in isolation; documented practice also describes verifying that a spark event aligns correctly relative to a separately measured compression stroke signal as a specific diagnostic check for timing correctness.

Can an engine's ignition system deliberately generate pulses that don't correspond to spark plug firing, for diagnostic testing purposes?

Yes — documented equipment description specifically explains that certain diagnostic interfaces can generate a modified timing signal carrying "dwell information of a dwell period insufficient to fire a spark plug," specifically to inhibit a selected cylinder from firing during a power-balance test, while still producing a genuine, documented timing signal to the ignition module for diagnostic monitoring purposes.