A load cell panel meter is an instrument cut into the front of a cabinet that powers a strain gauge sensor, reads the millivolts it returns and displays the result in whatever units the job is measured in. Balance and span are set from the keypad, so the display reads directly in pounds or kilograms rather than in volts.
What separates one of these from another is usually an assumption about where the sensor is. Many instruments quietly assume it is close by — a load cell on the same machine, a few feet of cable, a shared ground. This one assumes the opposite, and its specification sheet is an argument for that assumption from three directions.
First, and most importantly, the excitation supply has remote sense. That single phrase is the most valuable thing on this page and it appears in passing. Here is what it does.
An ordinary four-wire connection sends excitation down two wires and receives signal back on two more. Current flowing out to the sensor and back has to pass through the resistance of those excitation wires, and every bit of resistance drops a little voltage, so the sensor receives slightly less than the meter is sending. Published guidance describes the consequence exactly: your load cell thinks it is getting ten volts but is really seeing 9.8, and since output is proportional to excitation, your readings come out proportionally low. Not noisy, not unstable — low, steadily, by a percentage nobody can see.
Remote sense fixes it by measuring rather than assuming. Two additional wires run from the meter to the sensor's terminals and report back the voltage that actually arrived. Because almost no current flows in them, they lose nothing themselves, so what they report is the truth. The supply then adjusts its output until the sensor is receiving what it should. Published descriptions of six-wire practice put the benefit plainly: the sense leads allow the system to compensate for a voltage drop caused by cable length or by temperature change without affecting the measurement.
That second cause is the one that catches people out. Copper's resistance changes with temperature, so a long cable run through an unheated building is a different cable in February from the one it was in August. A four-wire installation drifts with the seasons and needs recalibrating to keep up. A sense-corrected one does not, because it re-measures continuously and never had to assume anything in the first place.
Second, the excitation is adjustable between 9 and 11 volts rather than fixed. That is not a convenience feature; it is the headroom the sense loop needs. A supply that can only produce one voltage cannot raise it to make up what a cable took away.
Third, it will withstand 2,500 volts peak of common mode voltage. That is an isolation figure rather than a rejection figure, and it is an order of magnitude beyond what a meter designed for a sensor in the next cabinet would need. It exists because when the sensor is genuinely somewhere else — a different machine, a different building, a structure with its own earth — the two ends of your cable are not at the same potential, and the difference is not always small.
Put together, this is an instrument designed on the assumption that the hard part of your installation is the distance between the sensor and the panel. Its own page says as much in one line: a voltage-to-frequency architecture chosen for noisy industrial applications.
The electrical chain holds no surprises. What is worth studying in this particular design is the set of trades it made — what it chose to spend its performance on, and what it deliberately gave up to pay for it.
It is deliberately slow, and that is the trade. The converter runs four times a second and the outputs update twice a second. Against instruments that convert sixty times a second those look like poor figures, and in one sense they are — but a voltage-to-frequency conversion that takes a quarter of a second is integrating over a great many mains cycles, and everything periodic in that window averages away. Slowness is where the immunity comes from. You are buying a reading you can trust in an electrically filthy environment, and paying for it in response time.
So be honest with yourself about what you are measuring. A tank filling, a hopper emptying, a cable under steady tension, a bin being loaded, a machine held at a set force — all of these change over seconds or minutes, and two updates a second is ample. The peak of a press stroke, the break point of a tensile test, a fastener letting go, the transient at the start of a motor — these are over long before this meter has finished thinking, and they want an instrument built the other way round.
The accuracy figure and the display are matched to each other, which is worth noticing. The meter is specified at 0.01 percent of full scale plus one count, on a four digit display reading to 9,999. Work it out: one hundredth of one percent of 9,999 is almost exactly one count. The analogue performance and the display resolution are the same size. A fifth digit would show you numbers the instrument cannot stand behind, which is why there isn't one. Four digits here is a match rather than a limitation, and it is the sign of an instrument specified coherently rather than to win a comparison table.
Temperature behaviour follows the same practical logic. Zero drifts by a tenth of a count per degree Celsius, which on this display means you would need a swing of ten degrees to move the reading by a single count. Span moves by 0.008 percent of reading per degree. For a meter living in a cabinet whose temperature wanders through the day, those are the numbers that decide whether the morning reading and the afternoon reading agree.
The excitation supply drives 90 milliamps, which sets how much you can hang on it. A single 350 ohm bridge at ten volts draws about 29 milliamps, so three of them in parallel is comfortable and a fourth is not. If your vessel sits on four mounts, that is a conversation to have before the steelwork is built rather than after — there are ways to arrange it, and they are all easier to design in than to retrofit.
Everything else is built for a person standing in front of a machine. A tare key on the front panel so the weight of a container or a fixture can be taken out without a calculation. Automatic capture of the highest reading seen, held until it is cleared. A security lockout code, because a setpoint that anybody can change is a setpoint nobody can rely on. Plug-in screw terminals, so a meter can be swapped without unpicking the wiring behind the panel — a small thing that matters enormously at two in the morning when a line is stopped.
Specifying one is largely a matter of being clear about how quickly the thing you are measuring moves, and how far away it is. Our applications engineers will go through both with you before you order.
Ask first how fast the measurement changes. This is the question that decides whether this is the right meter at all, and it is better answered honestly at the start. Loads that settle, fill, drain, hold or creep suit this instrument well. Loads that spike and vanish do not, and no amount of configuration will change that. We would far rather point you at something else than sell you the wrong architecture.
Then work out the cable run and the wiring you have. If the sensor is close and its cable is the one it was calibrated with, four wires are fine and the sense capability sits unused. If the run is long, if it passes through spaces at different temperatures, or if the cable has been extended or replaced, the sense connection is the reason to choose this meter and it should be wired properly from the start. Retrofitting two wires to an installed sensor is far more trouble than pulling six from the beginning.
Decide what has to act on the reading. The setpoint option gives two changeover relays rated for real current at mains voltage, which will operate a contactor, a valve or a beacon directly. The analog option produces an isolated 0–10 volt or 4–20 milliamp signal for a controller, a recorder or a data acquisition system. The serial option provides isolated RS232 for a computer. They combine, and the combinations are ordered as configured models rather than assembled from a shelf — so decide before ordering, and check with us before assuming an option can be added to a meter you already own.
Note that 4–20 milliamps is the safer of the two analog choices over any distance, for the same reason it always is: a broken wire reads as zero current, which is outside the valid range and unmistakably a fault, whereas a broken voltage connection reads as zero volts, which looks exactly like a legitimate reading of nothing.
Confirm the supply voltage before shipping. The meter runs from 115 or 230 volts AC rather than accepting anything in between, so tell us which one your panel provides. Nobody minds being asked; everybody minds unboxing the wrong one.
Check the cabinet's temperature, not the room's. The operating range runs from freezing to forty-five degrees Celsius. That covers most enclosures comfortably, but a sealed cabinet in direct sun, beside an oven, or packed with drives that dissipate heat can run considerably warmer inside than the air around it. If yours is one of those, measure it rather than estimating.
The cutout is a standard size, which matters more than it sounds. At 1.78 by 3.63 inches it drops into the same aperture as a great many other instruments, so replacing something already in a panel usually means unwiring the old one and fitting this one, with no metalwork at all.
Tell us the sensor, the cable length, how quickly the load changes and what has to happen when it reaches a limit, and we will confirm the configuration. The standard models ship from stock, and academic and research buyers should ask about the discount.
DPM-2 Load Cell Panel Meter Applications.
The Transducer Techniques DPM-2 is a voltage-to-frequency microprocessor based panel meter that accepts any full bridge transducer, with balance and span selectable from the front keypad so the display reads directly in engineering units, making it suited to the measurement, display and control requirements of noisy industrial applications.
- Industrial Weighing: Front panel tare and direct engineering unit display suit platform, bin and container weighing where a fixture or vessel weight has to be removed from the reading.
- Tank and Vessel Contents: Remote sense excitation keeps readings honest where the load cells are on the vessel and the meter is in a control room some distance away.
- Long Cable Installations: Sense-corrected excitation removes the proportional error that cable resistance introduces over a long run, and the seasonal drift that comes with it.
- Electrically Hostile Plant: A 2,500 volt peak common mode withstand suits installations where the sensor's ground and the panel's ground are not the same potential.
- Batch and Fill Control: The dual setpoint option operates valves, feeders or contactors directly as a vessel reaches target weight.
- Overload and Limit Alarms: Changeover relays trip an alarm, a brake or a drive when a load passes a threshold that should not be exceeded.
- Tension Monitoring: Steady web, wire, cable and rope tension displayed at the panel with an isolated analog output to a controller.
- Process Signal Conversion: The analog output option turns a load cell into a 4–20 mA process signal that any plant controller can accept.
- Maximum Load Recording: Automatic capture of the highest reading holds a peak for an operator to record where the load builds over seconds rather than milliseconds.
- Panel Replacement and Retrofit: A standard cutout and plug-in screw terminals allow an ageing instrument to be replaced without altering the panel or rewiring the installation.
The DPM-2 accepts any full bridge transducer and works with our full range of load cells, torque sensors and pressure transducers, with setpoint, analog output and serial communication options available.
Frequently Asked Questions
What kind of installation is the DPM-2 designed for?
One where the sensor is not next to the meter and the electrical environment is unkind. Its own description names noisy industrial applications, and three features back that up: excitation with remote sense, so a long cable does not falsify the reading; an adjustable excitation voltage, which is what makes the sense correction possible; and a 2,500 volt peak common mode withstand, which is an isolation figure suited to two ends of a cable sitting at genuinely different potentials. It accepts any full bridge transducer, with balance and span set from the keypad so the display reads in your own units.
What is remote sense, and why does it matter so much?
Two extra wires that run to the sensor's terminals and report back the voltage that actually arrived there. It matters because excitation current flowing down a cable loses voltage in the wire itself, so the sensor gets less than the meter sent — and since a strain gauge sensor's output is a proportion of its excitation, less excitation means a proportionally smaller signal and a reading that is quietly low. Published guidance describes exactly this: the cell thinks it is receiving ten volts but is really seeing 9.8, and the readings come out low to match. The sense wires carry almost no current, so they lose nothing themselves and report the truth, and the supply adjusts until the sensor has what it should. It is the difference between assuming and measuring.
Why is the excitation adjustable rather than fixed?
Because a supply that can only produce one voltage has nothing to correct with. The 9 to 11 volt range is the headroom the sense loop works within: if the cable is taking half a volt, the supply raises its output until the sensor is receiving the right amount. It also lets you trim the excitation to suit a particular sensor or to match an existing calibration. A fixed supply cannot do either, which is why an adjustable one and a sense connection belong together as parts of the same design rather than as two separate features.
How far can the load cell be from the meter?
Further than a four-wire connection would allow, which is the point, but there is still a limit and it depends on the cable rather than on the meter. What matters is the resistance of the excitation conductors and how much voltage the supply has in hand to compensate with. Heavier gauge conductors mean less loss and a longer usable run; several sensors on one supply mean more current and therefore more loss. Use properly specified shielded cable, keep it away from power wiring, and if the distance is substantial send us the length, the cable type and the number of sensors and we will confirm it works before you install it.
How accurate is the DPM-2, and why only four digits?
0.01 percent of full scale plus one count, with zero drifting a tenth of a count per degree Celsius and span 0.008 percent of reading per degree. The four digits are a deliberate match rather than a shortfall: one hundredth of a percent of a 9,999 count display works out at almost exactly one count, so the instrument's analogue accuracy and its display resolution are the same size. Adding a fifth digit would display numbers the electronics could not stand behind. Where you genuinely need to see finer changes than the accuracy can certify — watching for small movement rather than reporting an absolute value — that is a different requirement and a different instrument.
Why does the meter convert only four times a second?
Because that is where the noise immunity comes from. A voltage-to-frequency conversion taking a quarter of a second integrates across many mains cycles, and anything periodic within that window averages itself away before it ever reaches the display. Speed and immunity pull in opposite directions and this design chose immunity deliberately. The consequence is real and worth stating plainly: this meter suits loads that change over seconds and minutes, and it is the wrong instrument for capturing an event that is over in milliseconds.
What does a 2,500 volt common mode withstand actually mean?
It describes how much voltage can exist between the measuring circuit and the rest of the world without damaging anything or invalidating the measurement. In a plant, the ground at a machine on the far side of the building is not necessarily at the same potential as the ground in your control room, and the difference appears across your sensor cable whether you planned for it or not. A figure in the thousands of volts is generous headroom for that, which is why it is specified on an instrument intended for distant sensors. Rejection of interference riding on the signal is handled separately, and both matter.
What options are available, and how are they ordered?
Three, and they combine. The setpoint controller option adds two changeover relays for switching. The analog output option provides an isolated 0–10 volt or 4–20 milliamp signal. The serial option provides isolated RS232 for a computer connection. Every combination is available and each is ordered as its own configured model rather than being picked from a shelf and fitted afterwards, so the sensible approach is to decide what the meter has to do before you order. If you already own one and need to add something, ask us rather than assuming either way.
What will the setpoint relays switch?
Changeover contacts rated at 5 amps and 125 volts AC, which handles a contactor coil, a solenoid valve, a beacon or a small motor starter directly, without an interposing relay. Two of them, so two thresholds. Note the voltage rating rather than assuming it: 125 volts covers a North American control circuit comfortably but is not a 230 volt rating, so a coil at that voltage needs an interposing relay between the meter and the load. Bear in mind too that the outputs update twice a second, which is right for a filling or a limit application and too slow for anything that has to catch a fast event.
What panel cutout does the DPM-2 need?
1.78 inches high by 3.63 inches long, which is a standard instrument size rather than a proprietary one. That is genuinely useful on a retrofit, because it means an existing aperture very often takes this meter without any metalwork — you unwire the old instrument and fit this one. Combined with the plug-in screw terminals, which let the wiring be pulled off as a block, swapping an instrument becomes a job measured in minutes rather than a panel modification.
Questions From The Field
My readings are consistently a few percent low.
If the sensor is on a long cable and the sense wires are not connected, that is very likely your answer. Excitation lost in the cable means the sensor receives less than it should, output falls in proportion, and the error is steady, believable and invisible — it looks like a calibration problem rather than a wiring one. Check whether the sense terminals are wired through to the sensor or jumpered at the meter. If they are jumpered and the cable is long, wiring them properly will correct it. Also confirm nothing has been added to the cable run, since an extension changes the resistance the original calibration assumed.
The reading has shifted between summer and winter and nothing else changed.
Copper's resistance rises and falls with temperature, so a long cable run through an unheated space is genuinely a different cable at different times of year. On a four-wire connection that changes how much excitation the sensor receives, and the reading follows — which is why four-wire installations on long runs often need recalibrating seasonally. Sense wiring removes the problem at its root because it re-measures continuously rather than relying on an assumption made once. If your cable is long and the drift is annual, wire the sense connection through rather than recalibrating twice a year.
Can I use this meter to capture the peak of a press stroke?
Almost certainly not, and it is better to know now. The meter converts four times a second, so a press cycle lasting a fraction of a second is finished before a single conversion completes, and the maximum it records will be some accidental value rather than the true peak. The automatic maximum capture is there for loads that build over seconds — a vessel filling, a slow proof load, a gradual pull. For genuinely fast events you need an instrument sampling far more quickly, and we can point you at the right one. Tell us how long your event lasts and the answer is usually obvious.
My load cell only has four wires. Can I still use the sense inputs?
You link the sense terminals to the excitation terminals at the meter, and the meter then works as a conventional four-wire instrument. That is a perfectly normal arrangement and everything else functions as it should — but understand what you have given up, because the sense connection is now measuring the meter's own output rather than what reached the sensor, so any voltage lost in the cable is uncorrected. On a short cable that loss is negligible. On a long one it is exactly the error described above. If the run is long, the right answer is a six-wire sensor or a six-conductor cable to the sensor's terminals, and it is much easier to do at installation.
My panel runs on 230 volts. Is that a problem?
Not at all, but it is something to specify rather than assume. The meter is built for 115 or 230 volts AC rather than accepting the whole range in between, so tell us which your panel provides when you order and it will arrive correct. If you have inherited a meter and are unsure what it is set for, check before applying power rather than after — and if you are moving an instrument between sites with different supplies, ask us first.
The display is rock steady but I cannot get it to read zero.
A stable reading that will not zero is usually mechanical, and the stability is your clue that the electronics are behaving. Something is genuinely loading the sensor: a fixture's own weight, a cable or hose pulling on it, a container left in place, a piece of the structure resting where it should not, or a sensor that has been installed with a preload built in by over-tightened mountings. Take everything off the sensor and see whether it returns. If the offset is within range, the tare function will remove it, which is what tare is for. If it is a large fraction of the sensor's capacity, find the cause rather than taring it away, because you are giving up measuring range and possibly loading the sensor toward its limit.
Can I add the setpoint option to a meter I already have?
Ask us with the model number to hand rather than ordering a part on the assumption. The options are supplied as configured models, so a meter's capability is normally settled when it is built, and what is possible afterwards depends on which unit you have. It is a short conversation and it will get you a definite answer. Where retrofitting is not practical, there are usually other ways to achieve what you need — an external relay driven from an analog output, for instance — and we would rather discuss those than have you buy something that will not fit.
This meter is going into a wash-down area. Will it cope?
Talk to us before you install it, because no ingress protection rating is published for this instrument and we are not going to imply one. Some panel meters are sealed to a stated standard from the front and some are not, and in a wash-down environment that distinction decides whether the instrument survives. If your area gets hosed rather than merely wiped, the safe approach is either a meter with a published rating or this one mounted inside a sealed enclosure with a window. Tell us how wet the area actually gets and we will recommend accordingly — it is a much cheaper conversation than a failed instrument in a food or chemical plant.