LT DIN Rail Digital Transmitters with Serial Data Communication and Analog Outputs for Ratio, Product, Sum or Difference of 2 Rates or Total Applications

Ratio, Product, Sum & Difference DIN Rail Transmitter Frequently Asked Questions

Why does this transmitter only offer the Extended main board option, unlike the related Frequency/Rate/Period transmitter which offers both Standard and Extended?

Documented specification specifically states arithmetic functions A+B, A-B, AxB, A/B, and A/B-1 are made available by the Extended counter main board — since this page's entire purpose centers on those arithmetic functions, only the board option that actually provides them is documented as offered, unlike the related page where arithmetic is one optional capability among several the Extended board adds.

Can the Ratio (A/B) function be applied to totals as well as rates, and does the documented mixing-ratio application demonstrate this?

Yes — documented description specifically states ratio can be applied to scaled totals to compare two batches to be mixed, with one transmitter monitoring flow rate ratio and a second monitoring resulting batch totals; the general arithmetic functions are documented as applicable to rates, totals, square-root-extracted rates, and custom-curve-linearized values alike, not limited to instantaneous rate alone.

In the coating thickness application, why does the ratio specifically need Channel A (coating rate) divided by Channel B (film speed), rather than the reverse?

Documented example specifically assigns coating material application rate to Channel A and film speed to Channel B, with the A/B ratio representing coating thickness (volume of material per unit length of film) — since thickness is physically the amount of material applied divided by the length of film it's spread across, this specific channel assignment reflects the underlying physical relationship being measured, not an arbitrary choice.

Does the Draw function (A/B-1) require Channel A and Channel B to be measuring roller speeds specifically, or can it apply to other rate pairs?

Documented examples specifically describe draw applied to film elongation between rollers and to roller RPM differences for tensioning, but the underlying calculation (ratio minus 1) is a general-purpose relative-difference figure — any two rate inputs where the relative percentage difference between them is the meaningful quantity could use this same documented function, not exclusively roller-speed comparisons.

Why does high resolution matter specifically for the Draw function, more than it might for a simple ratio far from 1:1?

Documented guidance specifically notes the high resolution of Laureate dual-channel transmitters is ideal for comparison of rates that are close to each other — since draw is computed by subtracting 1 from a ratio that's typically very close to 1.000 in tensioning applications, small absolute differences in the underlying rates produce very small draw values, making fine resolution specifically necessary to meaningfully resolve those small values.

Does the inflow/outflow application require two separate flow meters feeding Channels A and B, or can it work from a single sensor?

Documented description specifically frames this as comparing "the inflow and outflow rates of a tank," implying two genuinely separate flow measurement points (one on the inflow line, one on the outflow line) feeding the two channels — the ratio and difference calculations are documented as meaningful specifically because they compare two independently measured flows, not a single sensor's reading processed twice.

Can the same physical transmitter be reconfigured to switch between different arithmetic functions (say, from A+B to A/B) without a hardware change?

Documented capability lists all five arithmetic functions (A+B, A-B, AxB, A/B, A/B-1) as available on the same Extended counter main board, configured via the same free Instrument Setup Software — this points to configuration-level flexibility to switch between functions on shared hardware, rather than requiring different hardware for each specific arithmetic operation.

Does the documented A+B "sum of parts carried by two conveyor belts" example require both belts to run at the same speed for the sum to be meaningful?

No — documented description specifically frames A+B as summing the rate of parts (or flow) from each channel independently, regardless of the underlying belt speeds; since each channel's pulse rate already reflects that channel's own actual part-carrying rate, the sum is meaningful as a combined total throughput figure even if the two belts operate at genuinely different speeds.

Does the output update rate formula (gate time + 30 ms + 0-2 signal periods) apply identically to a simple single-channel reading and to an arithmetic combination like A/B?

Documented specification presents this update rate formula as a general transmitter output characteristic rather than listing separate figures for single-channel versus arithmetic-combination outputs — since computing an arithmetic combination requires valid current readings from both channels A and B before the combination itself can be calculated, the practical update rate for an arithmetic result is governed by the same documented formula applied to whichever channel takes longer to produce a fresh reading.

Can the dual relay board alarm on the arithmetic result (such as the A/B ratio) directly, or only on the individual Channel A and Channel B readings?

Documented application examples specifically describe alarming the A/B ratio itself — the mixing ratio and coating thickness examples both specifically describe "transmitting and alarming" the ratio value, confirming the dual relay board can be configured to trigger directly off the computed arithmetic result, not solely off the two individual channel readings that feed into it.

Web Draw & Tension Control Questions From the Field

What specifically is "draw" or "draw ratio" in web handling, and how does it relate to a ratio like 1:1.05?

Documented terminology specifically explains that draw is sometimes called ratio control, with a stated example of setting ratio control to 1:1.05 being equivalent to 5% draw — this describes the downstream roller running that percentage faster than the upstream roller, deliberately stretching the web by that percentage as it passes between the two rollers.

What is "negative draw," and does it necessarily cause material to pile up as intuition might suggest?

Documented explanation specifically defines negative draw as driving a downstream roller at a lower surface speed than an upstream roller, which decreases the web's elongation and lowers its tension — but documented guidance specifically clarifies that a modest negative draw doesn't necessarily cause slack material buildup, since it may simply relax an already-stretched web to a lower tension rather than causing genuine material pileup, provided the negative draw doesn't exceed the entering web's existing strain.

Why might a process deliberately run in "draw control" mode rather than tension control mode?

Documented guidance specifically identifies applications where the critical variable is percent stretch itself rather than tension — for materials like fragile nonwovens or low-yield-point webs, documented guidance notes that running in tension control mode can create product variation, since the force needed to achieve a given stretch may vary, whereas draw control mode directly controls the percent stretch regardless of how much force that requires.

Does uneven tension between laminated web layers cause a specific, documented defect, and what is it called?

Yes — documented guidance specifically identifies "tunneling" as a delamination wrinkling defect that can occur when one web layer is strained significantly more than another during lamination; documented best practice specifically calls for tensioning individual webs so their strain is approximately equal before lamination, specifically to avoid this defect along with related curl problems.

Can web slip on a driven roller genuinely affect draw ratio accuracy, even if the roller's own commanded speed is correct?

Yes — documented field guidance specifically identifies web slip on follower drive rollers as a cause of lost tension control or draw ratio accuracy; even with a roller correctly driven at its commanded speed, slip between the web and the roller surface means the web's actual surface speed doesn't match the roller's speed, undermining the draw calculation's underlying assumption that roller surface speed equals web speed.

Does temperature or thermal deformation during processing (such as drying) affect draw and tension control accuracy?

Yes — documented research specifically describes how thermal deformation of a web during drying induces additional elongation beyond what mechanical draw alone accounts for, amplifying the impact of tension on final product quality; documented findings specifically note that accounting for this thermal behavior in the control model measurably reduced web strain variation compared to control approaches that didn't account for it.

Is there a documented range of typical draw or speed-ratio values used in web annealing or orientation processes?

Yes — one documented industrial process specifically describes an "annealing ratio" (the ratio of cooled to heated annealing roller surface speeds) with a typical documented value between 0.90 and 0.98, illustrating that draw-type speed ratios in real production processes are often fine-tuned within a fairly narrow documented range rather than set arbitrarily.

Does a dancer roller swinging to one extreme of its travel indicate a specific documented type of tension problem?

Yes — documented troubleshooting guidance specifically associates a dancer roller swinging to its full "dispensing" side with one category of tension variation issue, and swinging to its full "accumulating" side with a different, opposite category — the direction a dancer roller moves toward its travel limit is documented as a diagnostic indicator pointing toward which side of the tension control loop (feeding too fast or too slow relative to demand) is the underlying cause.