ABB AI845 DCS programming analog input unit
RMIO board specifications
Analogue inputs
Two programmable differential current inputs (0 mA / 4 mA ... 20 mA, Rin = 100 ohm)
and one programmable differential voltage input (-10 V / 0 V / 2 V ... +10 V,
Rin = 200 kohm).
The analogue inputs are galvanically isolated as a group.
Insulation test voltage 500 V AC, 1 min
Max. common mode voltage
between the channels
±15 V DC
Common mode rejection ratio > 60 dB at 50 Hz
Resolution 0.025% (12 bit) for the -10 V ... +10 V input. 0.5% (11 bit) for the 0 ... +10 V and
0 ... 20 mA inputs.
Inaccuracy ± 0.5% (Full Scale Range) at 25 °C (77 °F). Temperature coefficient: ± 100 ppm/°C
(± 56 ppm/°F), max.
Constant voltage output
Voltage +10 V DC, 0, -10 V DC ± 0.5% (Full Scale Range) at 25 °C (77 °F). Temperature
coefficient: ± 100 ppm/°C (± 56 ppm/°F) max.
Maximum load 10 mA
Applicable potentiometer 1 kohm to 10 kohm
Auxiliary power output
Voltage 24 V DC ± 10%, short circuit proof
Maximum current 250 mA (shared between this output and optional modules installed on the RMIO)
Analogue outputs
Two programmable current outputs: 0 (4) to 20 mA, RL < 700 ohm
Resolution 0.1% (10 bit)
Inaccuracy ± 1% (Full Scale Range) at 25 °C (77 °F). Temperature coefficient: ± 200 ppm/°C
(± 111 ppm/°F) max.
Digital inputs
Six programmable digital inputs (common ground: 24 V DC, -15% to +20%) and a
start interlock input. Group isolated, can be divided in two isolated groups (see
Isolation and grounding diagram below).
Thermistor input: 5 mA, < 1.5 kohm “1” (normal temperature), > 4 kohm “0”
(high temperature), open circuit “0” (high temperature).
Internal supply for digital inputs (+24 V DC): short-circuit proof. An external 24 V DC
supply can be used instead of the internal supply.
Insulation test voltage 500 V AC, 1 min
Logical thresholds < 8 V DC “0”, > 12 V DC “1”
Input current DI1 to DI 5: 10 mA, DI6: 5 mA
Filtering time constant 1 ms

Relay outputs
Three programmable relay outputs
Switching capacity 8 A at 24 V DC or 250 VAC, 0.4 A at 120 V DC
Minimum continuous current 5 mA rms at 24 V DC
Maximum continuous current 2 A rms
Insulation test voltage 4 kV AC, 1 minute
DDCS fibre optic link
With optional communication adapter module RDCO. Protocol: DDCS (ABB
Distributed Drives Communication System)
24 V DC power input
Voltage 24 V DC ± 10%
Typical current consumption
(without optional modules)
250 mA
Maximum current consumption 1200 mA (with optional modules inserted)
The terminals on the RMIO board as well as on the optional modules attachable to the board fulfil the Protective Extra
Low Voltage (PELV) requirements stated in EN 50178 provided that the external circuits connected to the terminals also
fulfil the requirements and the installation site is below 2000 m (6562 ft). Above 2000 m (6562 ft), see page 59.