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

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

Why use the ratio function instead of just monitoring both flow rates separately and comparing them manually?

Computing the ratio directly in the transmitter provides a single, continuously updated value suited to automated alarming and control — a mixing process can react to ratio drift in real time rather than relying on an operator or external system to compare two separate readings and calculate the relationship themselves.

Can the arithmetic functions be applied to totals as well as rates?

Yes — all five functions (A+B, A-B, AxB, A/B, A/B-1) can be applied to scaled totals just as they can to scaled rates, which is what makes it possible to compare two batch totals being mixed, not just their instantaneous flow rates.

Does the Ethernet interface affect measurement accuracy or update rate?

No — accuracy and update rate come from the same quartz-referenced signal conditioning used across the product line; Ethernet only changes how the reading is transmitted digitally rather than over serial data.

What's the difference between using the ratio function and the draw function for two similar speeds?

Ratio (A/B) reports the raw proportion between the two channels, while draw (A/B-1) reports that same relationship shifted so that equal speeds read as zero — making small deviations from a 1:1 relationship, like the slight elongation of film between rollers, much easier to read directly rather than parsing a ratio value close to 1.0.

Why does the mixing ratio application recommend a turbine flow meter specifically?

Turbine flow meters output a pulse train at a frequency proportional to flow rate, which matches directly with this transmitter's pulse-counting input channels; other flow-sensing technologies that don't produce a proportional pulse output would need additional signal conditioning before they could feed this transmitter's ratio function.

Can this transmitter alarm on the computed ratio itself, not just the two individual rates?

Yes — the computed arithmetic result (sum, difference, product, ratio, or draw) can be sent to the dual relay board for alarming, so a ratio drifting outside an acceptable band can trigger an alarm or control action directly from the combined value.

Does custom curve linearization need to be applied to both channels, or can it apply to just one?

Linearization is applied per input channel based on that channel's own transducer characteristics, so it's entirely possible to linearize one channel (say, a nonlinear turbine meter) while leaving the other channel's linear-output sensor unlinearized, before the two are combined arithmetically.

What's the benefit of high resolution specifically for the draw/elongation application?

When comparing two rates that are close to each other — like roller speeds with only slight tension-driven variation — a small absolute difference represents a large fraction of the meaningful signal; high resolution ensures that small, meaningful variation isn't lost in measurement noise or rounding.

Do I need a gateway device to connect this transmitter to my network?

No — the transmitter connects directly to a LAN via its own RJ45 jack over Modbus TCP, without requiring a separate RS485-to-Ethernet gateway.

Can multiple ratio/sum/difference transmitters be networked together?

Yes — the transmitter supports up to 247 digital addresses via Modbus TCP, allowing many individually addressable transmitters to coexist on the same Ethernet network.

LTE Ratio, Product, Sum, or Difference Transmitter Questions From the Field

My mixing ratio reads correctly at high flow but drifts at low flow — what's the likely cause?

Low-flow drift in a ratio calculation often traces back to one channel's flow meter (commonly a turbine meter) behaving nonlinearly at low flow rather than a fault in the ratio calculation itself; applying custom curve linearization to the affected channel is the standard fix.

My inflow/outflow comparison shows a nonzero net flow even though the tank level looks stable — why?

A small nonzero net flow reading with a visually stable tank level can simply reflect measurement resolution and normal sensor tolerance rather than an actual leak or fault; comparing the reported net flow rate against the tank's actual level trend over a longer period helps distinguish real net flow from measurement noise.

My coating thickness ratio alarm triggers during normal film speed changes — how is that addressed?

This usually points to the alarm deadband or response timing being too tight for the rate at which film speed changes during normal operation; widening the alarm deadband or adding a short delay before the alarm triggers typically resolves nuisance trips during expected speed transitions.

My transmitter isn't showing up on the network — what should I check first?

Confirming the transmitter's IP configuration matches what the network expects, and that the physical Ethernet cable and switch port are functioning, are the standard first checks before suspecting a transmitter fault.

My draw reading is noisy even though the two roller speeds seem stable — why?

Because draw compares two rates that are intentionally close to each other, any noise on either channel is amplified in the relative comparison; checking each channel's raw signal quality independently (proximity switch alignment, cable shielding) before assuming a computation fault is the standard first step.

Can noise on just one of the two input channels throw off an arithmetic result even if the other channel is clean?

Yes — since the arithmetic functions combine both channels, noise or instability on either single channel propagates into the combined result; isolating and testing each channel independently is the standard way to determine which channel is actually the source of an unstable arithmetic reading.

My Modbus TCP polling occasionally times out even though the transmitter appears connected — what's the likely cause?

Network congestion or too many devices polling the same transmitter simultaneously can cause intermittent timeouts; checking polling frequency from all connected clients and network traffic load is a common troubleshooting step.

My totalized ratio doesn't match what I calculate manually from the two individual totals — what should I check?

Confirming both channels are scaled to consistent units before the ratio is computed is the first step, since a ratio calculated from totals in mismatched units (like gallons on one channel and liters on the other) will produce a result that doesn't match a manual calculation done in a single consistent unit.