Sensoray 2426 - Manual (Page 8)

2426 Instruction Manual 6 Analog Interfaces
Chapter 5: Analog Interfaces
5.1 Analog Inputs
Six 12-bit, analog input channels are provided to enable
measurement of up to six external voltages. Each channel
implements a fully differential input pair so that either
single-ended or differential voltage measurements may be
made on any channel. Unused channels may be left
disconnected. External analog channels are numbered 0 to 5.
Figure 3: Analog Input Interface Block Diagram
All analog inputs have a fixed input voltage range of ±10V
with nominal 12 bit resolution. The analog input span extends
slightly beyond ±10V to guarantee a full ±10V measurement
range under worst-case conditions and to make it possible to
digitally calibrate the external channels.
Two internal reference channels supply precision reference
voltages (0V and +5V) to the ADC. Data from these references
can be used to digitally correct measurement errors caused by
aging and temperature variations.
5.1.1 Analog Input Scanning
All analog inputs (external and internal) are digitized by the
module once per millisecond. This scanning process runs
continuously and is independent of client requests for analog
input sample data.
When a client requests analog input data, the module returns
the most recent sample values for each channel along with
timestamps that indicates when the samples were acquired.
5.2 Analog Output
One 12-bit analog output channel (AOUT) is provided, with a
fixed output voltage range of ±10V. This output is well suited
for motor speed control or other general purpose uses.
Figure 4: Analog Output Interface Block Diagram
AOUT is referenced to AGND, so applications that require a
differential analog output will typically use the AOUT and
AGND signals as a differential pair.
The voltage produced at AOUT changes immediately in
response to client commands.
5.3 Analog Connector
Analog I/O connections are made through the 25-pin AIO
connector (see Figure 2 for connector location). The AIN and
AOUT interfaces both share the AIO connector.
ADC
Analog
Reference
Channel
Generator
Select
Register
Mux
Input
Protect
External
Analog
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D
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B
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Inputs
Table 2: AIO Connector Pin Assignments
Pin Name Function
2, 4, 6, 8,
10, 12, 13
AGND
Analog ground references for all AOUT and
AIN channels.
15, 17,
19, 21, 23
+24V
+24VDC outputs. These can be used to supply
operating power to external loads.
1 +AIN0 AIN channel 0 positive input
14 -AIN0 AIN channel 0 negative input
3 +AIN1 AIN channel 1 positive input
16 -AIN1 AIN channel 1 negative input
5 +AIN2 AIN channel 2 positive input
18 -AIN2 AIN channel 2 negative input
7 +AIN3 AIN channel 3 positive input
20 -AIN3 AIN channel 3 negative input
9 +AIN4 AIN channel 4 positive input
22 -AIN4 AIN channel 4 negative input
11 +AIN5 AIN channel 5 positive input
24 -AIN5 AIN channel 5 negative input
25 AOUT Analog output voltage
DAC
Reference
Generator
Buffer
Amplifier
I
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D
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B
u
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Analog
Output
Setpoint
Register