ABB Symphony Harmony Series Instruction page 54

Analog I/O
Analog Inputs
J17
1
2
FIELD
INPUT 3
4
Figure 2-2. Analog Input Circuit
WBPEEUI240769B0
The I/O modules can input four separate analog signals con-
figurable as voltage (1 to 5 VDC) single ended or differential, or
current (4 to 20 milliamperes) field powered. It allows for a
common mode (inputs change together proportionally) differ-
ential voltage of ±10 VDC. The I/O module output mode is
selectable: current or voltage.
The input conditioning block consists of two pole input filters
that reduce input signal noise (Fig. 2-2). Refer to Table
normal mode rejection (differential change) and common mode
rejection specifications for the differential inputs. The input
conditioning block consists of an I/E (current or voltage) con-
version resistor and a configuration jumper (for each channel)
to configure the I/O module to input current or voltage (single
ended or differential).
The input select block consists of an analog multiplexer and
an inverting difference amplifier. The multiplexer selects one of
the inputs or the reference block inputs (calibration voltages).
The difference amplifier converts the selected input to a single
ended signal.
The A/D converter block circuit changes the input signal to a
12-bit value that is sent to the I/O expander bus interface.
Analog I/O
1-4 for
TO INPUT
SELECT
BLOCK
T00325A
2 - 3