Industrial signal conditioner

01

Match input, output and isolation

Dataforth's catalogue describes its DSCA32 module as a single channel that filters, isolates, amplifies and converts a current input to a high-level output. It accepts 4–20 mA, 0–20 mA or ±20 mA and provides 0 to +10 V, 0–20 mA or 4–20 mA output, with 1500 Vrms transformer isolation on three ports (input, output and power), 105 dB common-mode rejection at 50 or 60 Hz, input protection to 240 VAC continuous, and transient protection to ANSI/IEEE C37.90.1. [1]

The catalogue's comparison table lists, by family, isolation of 1500 Vrms (three-way or two-way) or 500 Vrms, CMR from 100 to 160 dB, bandwidths from 3 Hz to 20 kHz and input withstand of 120 or 240 Vrms. Its DSCA range covers voltage, current, true-RMS, RTD, potentiometer, thermocouple, strain-gauge, frequency, 2-wire transmitter with loop power and output types. [1]

Linked suppliers list signal isolators for thermocouple input to DC current or voltage output, for 2-wire and 3-wire transmitter input with loop power provided [3] [4], analog signal isolators and isolated safety barriers [2], ultra-thin isolators [5] and active and passive isolators. [6]

Editorial note: the catalogue distinguishes three-way from two-way isolation; ask which ports (input, output, power) are isolated from each other and at what test voltage.

Give the supplier the input type and range (mA, V, mV, thermocouple type, RTD type and wiring, strain gauge, frequency), whether loop power must be supplied, output type and range, load resistance, isolation ports and test voltage, required accuracy and drift, bandwidth or response time, supply voltage, channel count, mounting, operating temperature, approvals (hazardous area, UL, CE) and quantity.

02

Check accuracy, drift, response time and loop power

For the DSCA32 the catalogue lists ±0.03% span accuracy (including linearity, hysteresis and repeatability) and ±0.01% span linearity at 25 °C and 24 VDC; offset drift of ±6 ppm/°C for voltage output and ±20 ppm/°C for current output; gain drift of ±40 ppm/°C; −3 dB bandwidth of 100 Hz with 100 dB per decade roll-off; and response time to 90% span of 5 ms. [1]

The same specification gives input resistance below 100 Ω, a maximum current-output load of 600 Ω, 15–30 VDC supply at 25 mA (voltage output) or 55 mA (current output), ±5% zero and span adjustment, dimensions of 75 × 22.5 × 105 mm for 35 mm DIN rail, operation from −40 to +80 °C and 0–95% non-condensing humidity, and emissions and immunity to EN 61000-6-4 and EN 61000-6-2. [1]

Editorial calculation: a 600 Ω maximum loop load at 20 mA means up to 12 V across the receiving input and wiring; a 250 Ω PLC input plus two 50 m runs of wire at 0.1 Ω/m (10 Ω) uses about 5.2 V, leaving margin. Over a 40 °C ambient swing, ±40 ppm/°C gain drift adds about ±0.16% of span. [1]

03

Compare what suppliers offer

Suppliers linked to this page list signal isolators and conditioners; each card links to the page reviewed.

The listings reviewed include DIN-rail isolators with thermocouple, transmitter, analog and digital inputs, isolated safety barriers for hazardous areas, and isolation amplifier modules. Ask each for the accuracy, drift, isolation test voltage, CMR and response time of the exact model. [2] [3] [4] [5] [6]

04

Trace what each stage controls

This is a functional reference built from the sources cited; it is not one maker's specification.

05

Fill the specification fields with values for your loop

A signal conditioner quotation needs values for your loop. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

06

Send the signal, isolation and power data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Input: [type; range; loop power needed?]
Output: [type; range; load Ω]
Isolation: [ports; Vrms]
Accuracy: [% span; drift]
Response: [ms or bandwidth]
Power: [supply V]
Mounting: [DIN rail; channels]
Approvals: [Ex; UL; CE]
Quantity: [units]

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