Analog Input Circuit - ABB Symphony Harmony Series Instruction

Analog I/O
This value is an analog count that corresponds to the input
voltage. Nominal input range is 1 to 5 VDC (4 to 20 milliam-
pere); however, it allows for a 0.75 to 5.25 VDC (three to
21 milliampere) input range which is ±6.25 percent of the
nominal input range span (4 VDC).
Analog Input Circuit Calibration
The reference block generates accurate 1 VDC and 5 VDC sig-
nals. The I/O module does not have potentiometers to adjust
zero offset and gain for the A/D converter circuits. Instead, the
controller reads the reference voltages once per minute to cali-
brate the zero percent (1 VDC) and 100 percent (5 VDC) points;
this calibration automatically corrects the measured values. It
is performed continuously to correct for drift and temperature
variations.
Analog Outputs
The D/A converter block is two separate D/A converters
(Figure 2-3). A four-bit microcontroller converts and checks
data integrity from the controller. Each D/A converts a 10-bit
digital value (analog count) from the microcontroller to an ana-
log output (1 to 5 VDC). To check module circuit integrity, the
outputs are fed back to the analog input section. The feedback
values (analog output digital values) are compared to the val-
ues that were sent to the analog output section to test the out-
put quality. This tests for an output circuit failure or an open
loop between the controller and I/O module.
The analog output default jumpers set the output values dur-
ing system startup or time-out. Refer to
this section. The analog outputs will go to zero percent or 100
percent output, or they will hold their current values depend-
ing on the setting of the default jumpers. Refer to
put Mode Jumpers (J9, J11, J13, J15) put Mode Jumpers (J9, J11, J13, J15) put Mode Jumpers (J9, J11, J13, J15) put Mode Jumpers (J9, J11, J13, J15)
The analog output mode jumpers set the type of output, either
current or voltage. If current mode is selected, the I/E circuits
on the I/O module convert the voltage from the D/A converter
to a current output. Refer to
(J9, J11, J13, J15) (J9, J11, J13, J15)
(J9, J11, J13, J15) (J9, J11, J13, J15)
2 - 4
NOTE: All the analog output activities are under microcontroller control.
in Section 3 for details.
Bus Fault Timer Bus Fault Timer
Bus Fault Timer Bus Fault Timer
in Section 3 for details.
Analog Output Mode Jumpers Analog Output Mode Jumpers
Analog Output Mode Jumpers Analog Output Mode Jumpers
in
Analog Out- Analog Out- Analog Out- Analog Out-
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