The CST ISIE 4-20mA signal isolator (signal splitter) isolates and splits analogue current/voltage signals: it accepts 4–20 mA, 0–10 mA, 0–20 mA, 0(1)–5 V or 0–10 V and provides 1 or 2 independent isolated outputs (1 in, 2 out) with ±0.1 % F.S. accuracy. It also supplies isolated 24 V loop power to 2-wire transmitters, so one sensor signal can be sent to two destinations (PLC and indicator, DCS and recorder…) without noise or ground loops.
Input, outputs and power supply are mutually isolated (≥1500 VAC), with digital internal calibration (no potentiometers) and automatic zero correction for fast response, low consumption and good thermal stability. The slim 12.7 mm housing mounts on 35 mm DIN rail to save panel space. Equipment Industrial Solution Co., Ltd (ISE) supplies the ISIE in the exact input/output configuration you need.
What is a 4-20mA signal splitter used for?
- Split one signal into two: a pressure, flow or level sensor feeds both the PLC and a panel indicator, or two different control systems.
- Signal isolation: eliminates noise and ground loops and protects PLC/DCS analogue cards from field overvoltage.
- Signal conversion: 4–20 mA to 0–10 V, 1–5 V and vice versa.
- Loop power for 2-wire transmitters: no separate sensor power supply needed.
Key features
- High accuracy ±0.1 % F.S. (at 25 °C), temperature drift only 40 ppm/°C.
- 3-way isolation input – output – supply, ≥1500 VAC dielectric strength, ≥100 MΩ insulation.
- 1 in 1 out or 1 in 2 out; 2 in 2 out also available.
- Transmitter supply: open-circuit ≤26 V, ≥23 V at full load.
- Digital calibration, no potentiometers, automatic zero – no drift over time.
- Status LEDs: power and per-channel fault/over-range.
- Response ≤0.5 s, output ripple ≤5 mVrms, EMC to IEC 61326-3.
- Slim 12.7 mm housing, 35 mm DIN rail mounting.
CST ISIE signal isolator specifications
| Parameter | Value |
|---|---|
| Input | Current: 0(4)–20 mA; 0–10 mA. Voltage: 0(1)–5 V; 0–10 V. Others on request |
| Input impedance | Current: approx. 100 Ω; 0(1)–5 V: ≥1 MΩ; 0–10 V: ≥2 MΩ |
| Output | Active current: 0(4)–20 mA; 0–10 mA. Passive current: 4–20 mA. Voltage: 0(1)–5 V; 0–10 V. Others on request |
| Output load | Active 0(4)–20 mA: ≤500 Ω; 0–10 mA: ≤1 kΩ. Passive: RL ≤ (U − 3)/0.02 Ω. Voltage 0(1)–5 V: ≥1 MΩ; 0–10 V: ≥2 MΩ |
| Output ripple | ≤5 mVrms (250 Ω load) |
| Transmitter supply | Open circuit ≤26 V; full load ≥23 V; ≥17.5 V at 20 mA output |
| Transfer accuracy | ±0.1 % F.S. (25 °C ±2 °C) |
| Temperature drift | 40 ppm/°C |
| Response time | ≤0.5 s |
| Dielectric strength | ≥1500 VAC, 1 min, 1 mA leakage (input / output / supply) |
| Insulation resistance | ≥100 MΩ (input / output / supply) |
| EMC | IEC 61326-3 |
| Power supply | 18–32 VDC (24 VDC typical) |
| Full-load power (24 VDC) | 1 output: 0.6 W; 2 outputs: 1.5 W |
| Operating temperature | −20 … +60 °C |
| Operating humidity | 10 … 90 % RH (40 °C) |
| Atmospheric pressure | 80 … 106 kPa |
| Storage temperature | −40 … +80 °C |
| Dimensions (W × H × D) | 12.7 × 110 × 118.9 mm |
| Mounting | 35 mm DIN rail |
Ordering code
Structure: ISIE X X X — 1st digit: input; 2nd digit: output channel 1; 3rd digit: output channel 2.
| Code | Signal |
|---|---|
| 1 | 4–20 mA |
| 2 | 1–5 V |
| 3 | 0–10 mA |
| 4 | 0–5 V |
| 5 | 0–10 V |
| 6 | 0–20 mA |
Examples: ISIE111 — 4–20 mA in, two 4–20 mA outputs (1-in-2-out 4-20mA splitter). ISIE115 — 4–20 mA in, channel 1 4–20 mA, channel 2 0–10 V.
Wiring and indicators
| Configuration | Input | Output 1 | Output 2 | 24 VDC supply |
|---|---|---|---|---|
| 1 in – 1 out | Pins 1, 2, 3 (2-wire or 3-wire transmitter) | Pins 5 (+), 6 (−) | – | Pins 9 (+), 10 (−) |
| 1 in – 2 out | Pins 1, 2, 3 | Pins 5 (+), 6 (−) | Pins 7 (+), 8 (−) | Pins 9 (+), 10 (−) |
| 2 in – 2 out | Ch1: pins 1, 2, 3; Ch2: pins 4, 5, 6 | Pins 7 (+), 8 (−) | Pins 10 (+), 11 (−) | Pins 14 (+), 15 (−) |
Please check against the label on the device.
- PWR LED (green): steady on when powered.
- OUT1, OUT2 LEDs (red): off in normal operation; flashing when the corresponding input is faulty; steady when the input is over-range.
Installation notes
- Mount vertically on 35 mm DIN rail, securely fixed, with good ventilation.
- Avoid strong vibration and electromagnetic interference beyond industrial class 3 (IEC 61000-4).
- Environment free of substances corrosive to metal and plastics.
Applications of 4-20mA signal isolators
- Splitting pressure, flow, level and temperature signals to PLC and indicators.
- Isolation between field and DCS/PLC/SCADA in oil & gas, petrochemical, power, metallurgy and manufacturing.
- Boiler control panels: splitting drum level and steam pressure signals to the controller and HMI.
- Fixing noisy or jumping signals when several devices share one 4–20 mA loop.
FAQ
Can two devices be connected in series on one 4–20 mA loop instead?
Possibly, if total load is low enough and the devices are not both grounded, but it easily causes noise, errors and loss of signal if one device fails. An isolating splitter creates two independent loops – safer and more stable.
Does a 2-wire sensor need a separate supply?
No. The ISIE provides isolated ~24 V loop power to 2-wire transmitters via the input terminals.
Active vs passive output?
An active output sources current into the load (for passive AI cards). A passive output needs loop power from the receiver (powered AI cards).
Related products
Where to buy the CST ISIE 4-20mA signal isolator?
EQUIPMENT INDUSTRIAL SOLUTION CO., LTD (ISE) – Ho Chi Minh City, Vietnam – supplies genuine the CST ISIE 4-20mA signal isolator with technical consulting, fast quotation and on-site commissioning support across Vietnam and Southeast Asia.
Contact us: Sales +84 909 617 185 – Technical +84 979 117 185 – Email: [email protected]
