LTE DIN Rail Digital Transmitters with Ethernet Communication and Analog Outputs for Analog Input Totalizer Applications

LTE Analog Input Totalizer Transmitter Frequently Asked Questions

Why does this LTE Analog Input Totalizer page document four serial protocols (Modbus TCP, Modbus RTU, Modbus ASCII, Laurel ASCII), unlike other LTE pages that document only Modbus TCP?

Documented specification specifically lists this broader protocol set for this particular transmitter model, distinct from the Modbus-TCP-only listing documented on several other LTE Series product pages — this reflects that documented protocol support can genuinely vary by specific LTE transmitter model, so the exact protocol set available should be confirmed against this specific product's own documented specification rather than assumed to match other LTE Series pages.

Why does totalized value calculation specifically use "the product of rate and time in seconds regardless of the selected gate time," rather than depending on gate time?

Documented description specifically distinguishes this from the rate reading's own update timing — since gate time governs how often the transmitter refreshes its rate calculation, but the accumulated total is documented as computed from rate multiplied by elapsed time independent of that gate time setting, this design ensures the running total stays mathematically consistent and doesn't drift based on whatever gate time happens to be configured for the rate display.

Why do the three signal input types (0-1 mA, 4-20 mA, 0-10V) have such different documented input resistance values (1.00 kΩ, 50 Ω, 1.01 MΩ)?

Documented specification lists these three distinct input resistance values without detailing the underlying circuit reasoning — this is consistent with each input type requiring an input impedance appropriate to its own signal characteristics: current-loop signals (0-1 mA, 4-20 mA) typically use a low burden resistance to develop a measurable voltage without excessively loading the current source, while a voltage input (0-10V) is documented with a much higher input resistance specifically to minimize loading on the voltage source.

Does achieving the documented 25 updates/second rate specifically require the signal to be at the VFC's minimum output frequency (10 kHz)?

Yes — documented phrasing specifically ties the 25/sec figure to "the lowest frequency of 10 kHz and the minimum gate time of 10 ms," identifying this as a specific combination of conditions rather than a rate achievable at any input signal level; this reflects that the update rate is documented as bounded by how long it takes to time a sufficient number of periods at the actual frequency the input signal is converted to.

Does the documented 1/rate function specifically require the Extended main board, or is it available on the Standard board?

Documented specification lists 1/rate specifically as an Extended main board capability, distinct from the Standard board's documented rate/total/square-root functions — this is consistent with 1/rate (time) being a more advanced processing function built on top of the underlying rate measurement the Standard board already provides, requiring the additional Extended board capability to compute and output that inverse relationship.

Does selecting VF1 (4-20 mA) versus VF2 (0-1 mA) versus VF3 (0-10V) change the documented ±0.01% FS ±1 count accuracy specification?

No — documented accuracy specification is listed once, applying generally across the analog input signal conditioner, without separate accuracy figures for VF1, VF2, or VF3 specifically; the choice between these three signal input types is documented as matching the transmitter to whatever signal format the connected transducer outputs, rather than trading off measurement accuracy between the three options.

Does the documented batch control capability on this analog-input totalizer require external relay hardware, or is it self-contained?

Documented description specifically notes batch operation applications "typically make use of optional dual solid state relays, which are available as options" — this indicates the relay hardware needed to actually control a fill valve or similar external device is documented as an optional add-on rather than automatically included, meaning the transmitter's batch control logic itself is built in, but the physical relay output hardware to act on that logic is a separate documented ordering option.

Why does span tempco use "% reading" while zero tempco uses "% FS" as their respective documented reference points?

Documented specification lists these with genuinely different reference bases — span tempco (±0.003% of reading/°C) scales with the actual measured value, consistent with span-related drift being proportional to signal magnitude, while zero tempco (±0.003% FS/°C) is referenced to full scale, consistent with zero-point drift being a roughly fixed offset independent of where in the range the actual reading falls; this distinction reflects the different physical origins of these two documented drift mechanisms.

Does the documented power consumption figures (2W typical, 3W with max excitation) differ from other LTE Series transmitters' documented power consumption?

Yes — this page documents notably lower power consumption (2W typical, 3W with max excitation) compared to the 2.5W typical / 4.0W max figures documented on several other LTE Series pages; this genuine difference reflects that documented power consumption varies by specific transmitter model and its particular signal conditioner board, so this analog-input totalizer's own figures shouldn't be assumed to match other LTE Series product pages.

Does custom curve linearization on this transmitter apply before or after the rate-to-total calculation?

The page documents custom curve linearization as correcting the underlying signal (for example, to extend transducer range and accuracy), with totals separately documented as calculated by multiplying rate by elapsed time — this is consistent with linearization being applied to correct the rate signal itself first, with the already-linearized rate then feeding into the documented total-accumulation calculation, rather than linearization being applied as a separate correction after totaling.

Voltage-to-Frequency Converter (VFC) Questions From the Field

What specifically is a voltage-to-frequency converter, and what makes its output fundamentally different from a typical analog-to-digital converter?

Documented explanation specifically describes a VFC as accepting an analog voltage or current input and producing an output pulse train whose frequency is proportional to the input's magnitude — documented comparison specifically notes this differs from typical ADCs that use parallel digital outputs, since a VFC's output is instead a serial pulse stream whose frequency itself directly carries the analog information, converted to a digital word by counting pulses over a fixed count/gate time.

Is there a documented practical formula for calculating how much count time a VFC-based conversion needs for a given resolution?

Yes — documented technical guidance specifically provides a formula relating required count time to the number of codes needed for a target resolution and the VFC's full-scale output frequency, with a specific documented worked example: a VFC with a 1 MHz full-scale frequency requires a count time of just over 0.262 seconds to achieve 16-bit resolution (1 part in 262,144).

Is inherent monotonicity documented as a genuine advantage of VFC-based analog-to-digital conversion compared to binary-weighted-network converters?

Yes — documented technical analysis specifically identifies this as a real, structural advantage: unlike converters based on binary-weighted networks, VFC-based conversion is documented as inherently monotonic under all supply and temperature conditions, meaning the digital output reliably increases as the analog input increases, without the risk of non-monotonic behavior that binary-weighted architectures can exhibit under certain conditions.

Does averaging multiple VFC pulse-count samples reduce quantization error at the same rate as simple statistical averaging would predict?

Documented technical analysis specifically notes VFC-based conversion can reduce quantization error faster than typical statistical averaging — specifically citing an error reduction rate of 1/N (where N is the number of samples) rather than the more commonly expected 1/√N rate seen in ordinary statistical averaging, attributed to the documented "no-loss" nature of VFC-based conversion during the counting process.

Is there a documented advantage to locating a VFC physically remote from its receiving counter, rather than co-located with it?

Yes — documented explanation specifically notes that because a VFC's signal is converted into an easily-transmitted serial pulse stream, the analog signal-conditioning circuitry can be physically located close to the actual sensor, with only the resulting pulse train needing to travel over distance to a remote counter; documented guidance specifically identifies this as particularly advantageous in multi-channel data acquisition systems using a "converter-per-channel" architecture.

Can a VFC be paired with a second VFC configured as a frequency-to-voltage converter (FVC) to transmit an analog signal across an isolation barrier?

Yes — documented technical guidance specifically describes this exact VFC-FVC combination as "a very useful way of sending a precision analog signal across an isolation barrier," since the pulse-stream output of the VFC can cross an isolation boundary (such as through an optical or transformer-coupled path) more readily than a raw analog signal, with the receiving FVC then reconstructing an analog output on the other side.

Is there a documented distinction between a standard VFC and a "synchronous VFC" (SVFC) used in precision multi-channel systems?

Yes — documented technical description specifically identifies a synchronous VFC as a form of VFC that utilizes an external clock to synchronize its frequency output, distinguishing it from a standard free-running VFC; this documented synchronization capability is specifically noted as valuable in precision, multi-channel data acquisition systems.

Are VFC-based ADC techniques still an active area of documented engineering development, or is this considered a mature, unchanging technology?

Documented recent research specifically continues developing VFC-based conversion techniques — one documented example describes an advanced voltage-to-frequency-to-digital conversion method specifically aimed at remote sensor and telemetry applications, addressing a documented "bottleneck" problem in the frequency-to-digital conversion stage through a proposed dependent-count method, indicating VFC-based conversion remains an area of genuine, ongoing documented technical refinement rather than a static, decades-frozen technology.