Description
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Model Number: IC670ALG230
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Manufacturer: GE Fanuc / Emerson
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Input Channels: 8 single-ended, common supply
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Input Range: 0-25 mA (over-range) / default 0-20 mA; 4-20 mA selectable via dip-switch / set-point
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Impedance: 2.87 kΩ (creates ≈ 1-5 V drop)
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Resolution: 12-bit (4 096 counts); 5 µA per LSB
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Accuracy: ±0.1 % full scale @ 25 °C; ±0.25 % over –20 °C … +70 °C
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Update Rate: 60 µs per channel (≈ 16 kHz aggregate)
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Power: 24 VDC bus-supplied; 25 mA module only + loop current (max 210 mA)
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Isolation: 1500 VAC for 1 min / 250 VAC continuous channel-to-logic
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Connector: 25-terminal integrated spring-clamp block (AWG 14-22)
- Environmental: –20 °C to +70 °C operational, conformal-coated, IP20 (IP54 with gasketed case)
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IC670ALG230
Field Application & Problem Solved
A remote I/O station on a cooling-tower doesn’t want to land eight 4-20 mA transmitters on a PLC rack 200 m away—it wants one card in the field. Slide the IC670ALG230 into a Bus Interface Unit, land two wires per loop, and you have eight isolated, 12-bit current inputs ready for PLC commands. When the card fails the loops go dead and the HMI flags “COMM FAIL”; swap the module (draw-out style), snap the 25-terminal plug back in, and the readings re-appear exactly as before—no software reload, no re-addressing. Found in every IC670 remote drop from water-treatment plants to wind-turbine nacelles. Value is distance: one card replaces eight analog isolators, a fuse block, and a handful of shield-terminals.
The 24 VDC bus must supply module current (25 mA) plus the sum of all loop currents (up to 160 mA). If the bus sags below 18 V the A/D reference collapses and readings drift. Meter 24 V under full load; if it dips, upsize the bus supply or add a local 24 V booster.
A small slide-switch on the side selects 0-20 mA or 4-20 mA. If you leave it at 0-20 mA the PLC sees 4096 counts @ 20 mA instead of 3200 counts, so your 12 mA reading is 25 % high. Always verify the switch position before you apply loops.
The 25-terminal block accepts AWG 14-22 one wire or two AWG 18. If you force two #14s the spring cracks and the channel drops out under vibration. Use a ferrule or step down to #18 for doubles—torque to 0.5 N·m.
IC670ALG230
The module is group-isolated; land shield drain at the module and at the PLC and you create a ground loop that shows up as 60 Hz ripple. Earth-ground the shield at the PLC only—float it at the module.
IC670ALG230 is a remote I/O slice frozen in 1995 silicon. A 12-bit ADC multiplexes eight channels, creates a 1-5 V drop across the 2.87 kΩ resistor, and ships the counts to the Bus Interface Unit over the internal parallel bus. Because the module is group-isolated and fuse-less you can swap it hot—just kill the 24 V field supply first or you’ll arc-weld the 25-terminal plug. Treat the loop wires like instrumentation cable and the card will keep the transmitters talking for another thirty years
