Two analog inputs, 1 ms conversion, current lifecycle
The Siemens 6ES7123-1GB60-0AB0 is a 2-channel analog input module for the SIMATIC S7-1200 system, occupying 1 of the 8 available slots in the CPU rack. It measures 10 mm wide by 64 mm high by 51 mm deep, fitting into the standard DIN-rail mounted assembly without crowding adjacent modules. Each input is configurable for 4 mA to 20 mA (with 11-bit resolution including overrange) or −20 mA to +20 mA (12-bit including sign). The basic conversion time is 1 ms per channel, which sets the update rate for the process image — fast enough for most analog process signals but not for high-speed dynamic measurements.
Signal conditioning and wiring constraints
The module supports 4-wire transducers directly, so loop-powered transmitters connect without an external supply — the module provides the excitation. Input resistance is 50 Ω for the 4-20 mA range and 50 kΩ for the ±20 mA range, which matters when budgeting the loop voltage drop across long cable runs. Digital filtering is parameterizable in four stages (1×, 8×, 64×, 128× cycle time) to suppress noise on the signal. The usable terminal block is the TB 16IM-SC, which is ordered separately. Maximum shielded cable length is 200 m — adequate for most plant-floor runs but a constraint for remote field devices beyond that distance. Crosstalk between inputs is a minimum of 50 dB at 50/60 Hz, and common-mode interference rejection is also 50 dB with USS below 2.5 V. There is no channel-to-channel isolation, so adjacent channels share a common reference — plan the wiring accordingly when mixing signal types on the same module.