Digital Panel Meter for Rate, Totalizer with Functions A+B, A-B, AxB, A/B, A/B-1 Applications

Ratio & Draw Digital Panel Meter Frequently Asked Questions

Why does this particular configuration include AxB, when other Laureate ratio/draw documentation sometimes lists only A+B, A-B, A/B, and A/B-1?

This specific product listing documents AxB as part of the available function set alongside the other four operations — since documented function availability can vary by specific board and firmware configuration across the Laureate product line, confirming the exact arithmetic functions available against the specific meter configuration in hand is worth doing when a particular function like AxB is a hard requirement.

What kind of real application would specifically use AxB rather than one of the other four arithmetic functions?

A documented general use case for multiplication between two channels is mass flow calculation, where volumetric flow rate (Channel A) is multiplied by a density or concentration value (Channel B) to yield mass flow or dosing rate — this is a genuinely different calculation than the addition, subtraction, or ratio operations, which is why having AxB available alongside them broadens the range of solvable applications.

Why does the meter offer nine different minimum-signal ranges instead of a single universal sensitivity threshold?

The documented signal compatibility spans from millivolt-level magnetic pickups up to multi-volt logic and 250 Vac line-level inputs — a single fixed sensitivity couldn't reliably trigger on the smallest signals without risking false triggering from noise on larger ones, so nine selectable ranges let the trigger threshold be matched to whatever specific sensor is actually connected to each channel.

Does the six-digit resolution documented for draw and ratio results apply equally across both A+B/A-B and A/B/A/B-1 outputs?

The documented six-digit precision specifically describes the ratio/draw result display, achieved via the 0.00001 to 100000 multiplier and adjustable decimal point — since A+B and A-B are simpler additive operations on already-scaled engineering-unit values rather than a ratio calculation, their precision is governed by the underlying channel scaling rather than this specific multiplier mechanism documented for ratio/draw.

Can custom curve linearization be applied to a signal before it's used in an arithmetic combination like A/B?

The Extended board's linearization capability is documented generally as correcting a signal's raw nonlinearity into an accurate engineering-unit reading; since arithmetic functions operate on already-scaled channel values, a linearized Channel A or B reading feeding into an A/B or A-B calculation would carry that correction through into the arithmetic result, rather than the arithmetic function needing to separately account for the raw signal's nonlinearity.

Why does Channel B's maximum frequency (250 kHz) matter less for most ratio/draw applications than it might for other counter modes?

Ratio and draw applications typically involve two signals expected to be reasonably close in frequency to each other (matched roller speeds, synchronized conveyors, comparable flow rates) — for these use cases, the 250 kHz ceiling on Channel B rarely becomes a limiting factor, though confirming neither expected signal genuinely needs to exceed that ceiling remains worth checking if it's applied specifically to Channel B.

Does peak and valley capture apply to the arithmetic combination result, or only to the raw Channel A/B readings?

Peak and valley capture is documented as a general meter capability applied to the meter's currently configured display value — since the arithmetic combination (such as A/B) is itself a displayable, computed value, the same peak/valley capture mechanism applies to it the same way it would to a raw channel reading, letting an application capture the highest or lowest ratio/draw value reached during a process.

Can the totalized (rather than instantaneous rate) values of Channel A and B be used in the arithmetic functions, or only rate?

Documented capability specifically states these functions apply to rate or total after scaling to engineering units — meaning A/B, A-B, and the other functions can be computed on totalized volumes just as readily as on instantaneous rates, supporting applications like verifying a completed batch's total ingredient ratio rather than only monitoring the live ratio during the process.

Does entering XXXXEX scientific notation display mode affect the accuracy of an arithmetic combination like A+B?

No — this is documented specifically as a display-range accommodation once a value exceeds the standard ±999,999 count range, keeping very large summed or totalized values representable on the six-digit display without changing the underlying calculation's accuracy.

Does the noise filter setting (1 MHz/30 kHz/250 Hz) need to be matched on both Channel A and Channel B, or can each channel use a different setting?

Documented specifications describe noise filter and contact debounce as selectable settings on the FR signal conditioner board without indicating a requirement that both channels share an identical setting — since Channel A and Channel B often connect to genuinely different sensor types in ratio/draw applications (such as a flow meter on one channel and a proximity switch on the other), independently matching each channel's filter setting to its own connected sensor's noise characteristics is the more practical approach where the firmware allows it.

Flow Ratio Control & Proportional Blending Questions From the Field

In a two-stream ratio control system, what's the practical difference between the "wild" stream and the "dependent" or controlled stream?

Documented ratio control architecture specifically designates one stream (such as cement feed in a grouting application) as the "wild" stream, whose flow isn't directly controlled by the ratio system but instead varies due to upstream factors like hopper level or feeder inconsistency — the second, "dependent" stream's flow controller then continuously adjusts its own setpoint to track the wild stream's actual measured rate at the correct target proportion.

Why does documented guidance specifically recommend against derivative (D) action in flow ratio control loops?

Documented process control guidance specifically explains that derivative action amplifies high-frequency noise, and flow signals from turbulent flow or pump pulsation are inherently noisy — this makes derivative control action counterproductive in flow loops specifically, which is why proportional-integral (PI) control, without derivative, is documented as the standard approach for tuning ratio-dependent flow controllers.

Do two chemical injection devices of the identical model number reliably deliver identical, interchangeable calibration curves?

No — documented field testing specifically found that injection devices sharing the same model number do not deliver identical calibration curves, and that a manufacturer's generic calibration curve may not be appropriate for the actual operating conditions of a specific installation, meaning individual device calibration (not reliance on a nameplate spec) is documented as necessary for accurate ratio dosing.

Does outlet pressure genuinely affect a chemical injection device's delivery rate independent of its nominal setting?

Yes — documented testing across piston, diaphragm, and venturi-type injection devices specifically found that outlet pressure significantly affects the slope of the calibration curve, meaning a device calibrated at one pressure can deliver a meaningfully different actual ratio if operating pressure changes, which is a real, documented source of ratio drift beyond simple setpoint accuracy.

Why do some documented blending control algorithms use PID rather than simple proportional control for maintaining a target blend ratio?

Documented performance comparisons specifically show that a simple proportional-only algorithm settles at a steady-state error slightly below the desired ratio, a proportional-integral algorithm eventually converges to the correct ratio but with oscillation, while a full PID algorithm settles at the desired ratio quickly and without significant oscillation — illustrating a genuine, measurable performance difference between control strategies for the same blending task.

How do some documented precision blending systems detect and correct for cumulative ratio drift over many dosing cycles?

Documented precision blending patents specifically describe checking each stream's actual pulse count against its calibrated target count at the end of every dose cycle, adjusting the next cycle's target by the measured error — this cycle-by-cycle correction is specifically documented as preventing long-term cumulative ratio error from ever accumulating across many dosing cycles, rather than relying on the original calibration remaining valid indefinitely.

Does documented practice recommend periodically re-verifying a ratio control system's calibration even after an accurate initial setup?

Yes — documented blending system guidance specifically describes periodically prompting operators to collect a ratio dose sample from each operating stream after a set number of dosing cycles, specifically to validate the ongoing calibration accuracy of each stream — treating the original calibration as something that needs periodic re-verification rather than a permanently valid, one-time setup.

Can mechanical wear in a flow meter genuinely change a ratio control system's accuracy over time, even without any electronic fault?

Yes — documented analysis of positive displacement meter calibration specifically notes that mechanical wear changes the meter's internal geometry over time, causing its accuracy to drift from its original factory calibration — this is a purely mechanical degradation mechanism, distinct from any electronic or sensor fault, which is why documented practice recommends periodic field recalibration (using a calibrated "prover" reference) rather than relying solely on factory calibration indefinitely.