ABB Symphony Harmony Series Instruction page 59

Module Data
This intergrated circuit provides the following functions:
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Module Data
Function code 79 in the controller configuration accesses the
I/O module on the I/O expander bus. It also allows the con-
troller to automatically read input data or status data from the
I/O module, and write output data to it. This data is output by
the buffer circuits to the I/O expander bus interface (Fig. 2-1).
The I/O module address in FC 79 must be the same as the
address set on I/O address dipswitch (S1).
I/O Data
I/O data is analog input, digital input, and digital and analog
output readback values that the controller reads from the I/O
module. It is also analog and digital output values that the
controller sends to the I/O module. The controller uses this
data to monitor and control a process, and verify I/O module
operation.
Analog input data consists of analog counts from the A/D con-
verter. Analog counts are digital values that correspond to
analog signals; the A/D performs the conversion. The signals
converted include the four analog inputs, two reference volt-
ages (1 VDC and 5 VDC) and two analog output readback val-
ues. The controller reads each of these count values once every
execution cycle. Each analog input count value corresponds to
an analog input voltage. Reference voltage values are read by
the controller to verify A/D converter integrity. It reads the two
analog output values to adjust the analog outputs and check
for output circuit failures.
The controller reads a one byte value that consists of digital
output readback values and digital input values. The digital
input values indicate the digital input states. Each bit corre-
sponds to one input; the bit value reflects the state of that
input, either open (logic zero) or closed (logic one). Digital out-
put readback data reflects the output states. The controller
2 - 8
Address comparison and detection.
Function code latching and decoding.
Read strobe generation.
Data line filtering of bus signals.
On-board bus drivers.
WBPEEUI240769B0