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

LTE Ratio, Product, Sum & Difference Transmitter Frequently Asked Questions

Why does documented ratio-of-totals mixing comparison specifically require two separate transmitters (one for rate ratio, one for batch totals) rather than one transmitter tracking both?

Documented description specifically states "one transmitter is used to monitor the ratio of flow rates, and a second transmitter to monitor the resulting batch totals" — since a single transmitter is documented elsewhere as capable of tracking either rate-based or total-based arithmetic functions in a given configuration, monitoring both the real-time rate ratio and the accumulated total ratio simultaneously is documented as requiring two separately configured transmitters rather than one unit doing both at once.

Why does the coating thickness application specifically use flow rate (Channel A) divided by film speed (Channel B), rather than the reverse ratio?

Documented description specifically frames the A/B ratio as assuring "an even thickness of coating material is applied as the speed of the film varies" — this specific ratio direction (coating rate over film speed) is consistent with the underlying physical relationship where coat weight per unit area depends on how much material is deposited per unit of film length; a change in film speed alone, without a matching Channel A rate change, would directly shift this specific ratio and signal a thickness deviation.

Can arithmetic functions A+B, A-B, AxB, A/B, and A/B-1 all be simultaneously active on a single transmitter, or is only one function active at a time?

The page documents these as five distinct arithmetic function options made available by the Extended board, illustrated through separate application examples each using a specific single function — this is consistent with a given transmitter configuration being set to output one selected arithmetic combination at a time, rather than simultaneously computing and outputting all five functions from the same unit.

Does applying an arithmetic function like A/B to "totals after custom curve linearization" require the linearization to be applied identically to both Channel A and Channel B?

The page documents custom curve linearization as an available processing step applicable to rates or totals before the arithmetic function is computed, without specifying whether Channel A and Channel B require identical or independently configured linearization curves — since A and B can represent genuinely different physical measurements (such as a coating rate and an unrelated film speed), independently linearizing each channel to its own respective sensor's nonlinearity is consistent with the documented architecture, rather than assuming a single shared linearization curve applies to both.

Why does documented draw measurement (A/B-1) specifically benefit from the transmitter's high resolution when comparing rates that are close to each other?

Documented description 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 calculated by subtracting 1 from a ratio that, in a well-tensioned system, sits very close to 1.0, the meaningful signal (the small deviation from exactly 1.0) is a small difference between two large, nearly equal numbers, which is precisely the scenario where high resolution is documented as necessary to detect genuine, small variations rather than losing them in quantization noise.

Does this LTE Ratio/Sum/Difference transmitter's documented Modbus TCP-only protocol limit compatibility compared to the RS232/RS485 LT Series variant?

Yes — this page documents Modbus TCP specifically as the supported Ethernet Data I/O protocol at digital address 247, while the LT Series serial variant is documented elsewhere as separately supporting Modbus RTU/ASCII and Laurel Custom ASCII; a control system needing a protocol other than Modbus TCP would need to reference the LT Series serial variant rather than this LTE Ethernet variant.

Does the documented conveyor synchronization application require both proximity switches to sense the same type of rotating feature (gear teeth versus spokes) on their respective drive wheels?

The page documents this application as using "proximity switches which sense gear teeth or spokes of rotating drive wheels" without requiring both switches to sense the identical feature type — since the transmitter is documented as processing each channel's raw pulse rate independently before computing the ratio, and the ratio ultimately reflects each wheel's rotational speed rather than the specific mechanical feature triggering each pulse, using gear teeth on one line and spokes on another would still be consistent with a valid speed-ratio comparison, provided each channel's scaling correctly accounts for its own pulse-per-revolution count.

Does selecting the Extended main board (required for arithmetic functions) change the transmitter's documented base pulse input frequency range?

No — documented frequency ranges (0.005 Hz to 1 MHz on Channel A, 0.005 Hz to 250 kHz on Channel B) are listed under the general Pulse Inputs specification without a separate, narrower range specifically tied to Extended board operation; the Extended board is documented as adding arithmetic and linearization processing capability on top of the same underlying pulse input hardware and frequency range shared with the Standard board.

Can the same physical transmitter output the A/B ratio via its analog 4-20 mA output while simultaneously transmitting the raw Channel A and B rates via Ethernet?

The page documents the analog output as tracking the selected arithmetic function (such as A/B), while separately noting "all signal or alarm data can further be transmitted" via serial data — this is consistent with the calculated arithmetic result being the value driving the analog output, while the underlying individual channel data remains simultaneously accessible via the digital Ethernet/Modbus TCP interface, rather than the analog output and digital data stream being restricted to showing identical single values.

Does the documented note that arithmetic functions apply to "square root of rates" specifically address flow meters that produce a differential-pressure-based signal?

The page documents square root extraction as a general available processing option applicable to rates (alongside linear rates and custom curve linearized rates), without restricting it specifically to differential-pressure flow meters — however, square root extraction is a documented technique commonly associated with linearizing differential-pressure-type flow signals specifically, so this option is consistent with being relevant when either Channel A or B (or both) originates from that type of flow-sensing technology.

Coating Thickness Control Ratio Questions From the Field

Why does wet coating thickness fundamentally depend on the ratio of flow rate to line speed rather than either parameter alone?

Documented technical description specifically defines wet coating thickness through a formula relating coating flow rate, coating width, and substrate velocity — since the same total volume of coating material spread over a faster-moving substrate results in a thinner deposited layer, and spread over a slower-moving substrate results in a thicker layer, the documented relationship shows thickness is inherently a function of the flow-rate-to-speed ratio, not either parameter considered in isolation.

Does the relationship between gravure roll speed ratio and coating thickness behave the same way across the entire ratio range, or does it reverse at some point?

Documented patent description specifically identifies a reversal point at a gravure-to-web speed ratio of 2.0 — below this ratio, increasing the speed ratio is documented as increasing coating thickness, while above a ratio of 2.0, the documented relationship reverses, and further increasing the speed ratio actually decreases coating thickness, illustrating that this ratio-to-thickness relationship is not simply monotonic across its full range.

Is there a documented typical coating uniformity specification achievable with precision ratio-based coating methods like slot die coating?

Yes — documented industry figures specifically cite slot die coating as capable of achieving film thickness variation of less than ±2%, with some processes reaching ±1%, across a documented wide range of applicable liquid viscosities (roughly 10 to 10,000 cP); these documented figures illustrate the level of precision achievable when flow rate and line speed are tightly ratio-controlled.

Does increasing coating solution concentration (rather than adjusting the speed ratio) also affect achievable coating thickness in ratio-controlled coating processes?

Yes — documented experimental data specifically shows that at a constant web speed, coating thickness increases with increasing roller speed and increasing solution concentration, with one documented example showing coating thickness effects from doubling concentration from 6 wt.% to 12 wt.%; this indicates speed ratio is one documented control variable among several (including concentration) that jointly determine final coating thickness.

Is there a documented "low-flow limit" that constrains how thin a coating can be produced for a given flow rate and coating speed?

Yes — documented process engineering analysis specifically identifies a low-flow limit representing the minimum wet thickness achievable for a specified capillary number and coating gap, which is also documented as functioning as an upper bound on coating speed for a given flow rate; this documented physical limit means coating thickness can't simply be reduced indefinitely by increasing line speed relative to flow rate without eventually encountering process instability.

Does operating at certain gravure-to-web speed ratios risk producing visibly defective coatings, independent of the targeted average thickness?

Yes — documented experimental findings specifically identify speed ratios in the range of roughly 2 to 3.2 as producing highly defected coatings of limited practical utility for one studied material system, while documented results show defect-free coatings were achievable specifically at lower speed ratios combined with higher web speeds; this indicates certain ratio ranges carry a documented defect risk independent of whether the resulting average thickness happens to be on target.

In multi-layer or multi-station coating systems, is ratio-based flow control documented as extending beyond a single flow-to-speed relationship?

Yes — documented patent description specifically discusses comparing the sum of flow rates across multiple slot dies feeding an upper coating layer against the sum of flow rates feeding a lower layer, adjusting pump RPM specifically to bring that inter-layer ratio to a target value; this documented multi-layer ratio control represents a more complex application of the same underlying flow-ratio principle used in simpler single-layer coating thickness control.

Does the specific coating method chosen (slot die versus gravure versus comma coating) change how directly flow-rate-to-speed ratio determines final thickness?

Yes, to varying degrees — documented comparison specifically notes gravure coating thickness is influenced by the physical cell pattern engraved on the roller (best suited to lower-viscosity liquids under about 3000 cP), while comma coating thickness is instead controlled primarily by adjusting the physical gap between the coating head and substrate; slot die coating is documented as having the most direct, simple relationship between flow rate, coating speed, and resulting wet thickness among these three methods.