ibaNet750-455/4-AI 4-20mA

The I/O module provides one status byte (8 bits) and one data word (16 bits) per channel. 

Whether the status byte can be read out via the fieldbus depends on how diagnostic information is transmitted by the corresponding fieldbus or the head station used. 

In any case, the status byte can be read out via the service interface of the head station using the WAGO-I/O-CHECK commissioning tool.

The I/O module captures the input current range 4 mA … 20 mA with a resolution of 12 bits. 

The measured value is given in two’s complement representation, and the numerical value is mapped to bits B15 … B4 of the data word (bit 15 is the sign bit).

Bits B3 and B2 are reserved and can take a value of 0 or 1. Bits B1 and B0 contain diagnostic information. In the event of measurement overrange or underrange or wire break, the I/O module transmits the next displayable measured value and sets B0 and B1 to a value of 1. Simplified Interpretation of the Measured Value A simpler way to obtain the measured value is to interpret the entire data word as a 16-bit integer value.

e measurement range is then scaled to the numerical value range from 0x0000 to 0x7FFF. The decimal places of the resulting analog value corresponding to the lower four bits, however, must be ignored.