Jäger ADwin-Gold II, Manual

Page: 17 / 224

ADwin-Gold II , Manual February 2013
11
Analog Inputs and Outputs
ADwin
5.1 Analog Inputs and Outputs
In order to operate the system’s BNC plugs without any interferences, isolated BNC
connectors are necessary. Otherwise there will be the danger of damages caused by
ESD or short circuits at the inputs. This will be the case when using not isolated BNC
T-pieces.
The ADwin-Gold II device has to be connected to earth, in order to execute measure-
ment tasks without any interferences. Connect the GND plug via a low-impedance
solid-type cable with the central earth connection point of your device.
The power supply from the power adapter at the computer also connects the earth of
the
ADwin-Gold II system with the earth of the computer. If you do not operate the PC
and the ADwin-Gold II system in the same place, you should not use the power supplied
by the PC but an external power supply unit which is earth-free, in order to avoid influ-
ences by different ground reference potentials.
In addition to the description of the inputs and outputs you will find notes below for the
conversion of digits into voltage values and for the input settings of the analog inputs.
For fast and easy programming there are standard instructions available in the standard
instructions compiler
ADbasic , which enable a user to easily measure or output data
(see
ADC
or
DAC
, page 60 ). Use other instructions only if extremely time-critical or spe-
cial tasks require to do so. (See also ADbasic manual).
5.1.1 Analog Inputs
2 Multiplexers The system has 16 analog inputs IN1 … IN16. The inputs with odd numbers (1, 3, …
15) are allocated to multiplexer 1, those with even numbers (2, 4, … 16) to
multiplexer 2. The output of each multiplexer is connected to both a 14 bit-ADC and a
16 bit-ADC (see also "
Block diagram ADwin-Gold II ", page 5 ).
Differential The analog inputs are differential.For each of the measurement channels there is a pos-
itive and a negative input, between them the voltage difference is measured (but not
free of potential). Both, the positive and negative input have to be connected.
The inputs are equipped with male BNC-plugs, which are arranged in 2 rows; below, the
inputs are connected to the DSub-connector ANALOG IN. At the BNC-plugs, the posi-
tive input is the inner conductor, the negative input is the outer conductor.
Fig. 5 – Pin assignment of analog inputs (DSub)
Please note, that the inputs do need a mass connection between the system’s GND-
plug and the signal source. This is in addition to the connections to the positive and neg-
ative input.
Fig. 6 – Input circuitry of an analog input
ANALOG IN 1…8 ANALOG IN 9…16
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24 25
A
In
1
(+
)
A
In
2
(+
)
A
In
3
(+
)
A
In
4
(+
)
A
In
5
(+
)
A
In
6
(+
)
A
In
7
(+
)
A
In
8
(+
)
AG
N
D
AG
N
D
A
In
1 (-
)
A
In
2 (-
)
A
In
3 (-
)
A
In
4 (-
)
A
In
5 (-
)
A
In
6 (-
)
A
In
7 (-
)
A
In
8 (-
)
+
5
V
(<
100m
A
)
AG
N
D
RE
S
E
R
V
E
D
R
E
S
E
R
VED
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24 25
A
In
9
(+
)
AI
n
1
0
(
+
)
AI
n
1
1
(
+
)
AI
n
1
2
(
+
)
AI
n
1
3
(
+
)
AI
n
1
4
(
+
)
AI
n
1
5
(
+
)
AI
n
1
6
(
+
)
AG
N
D
AG
N
D
A
In
9 (-
)
A
In 10
(-
)
A
In 11
(-
)
A
In 12
(-
)
A
In 13
(-
)
A
In 14
(-
)
A
In 15
(-
)
A
In 16
(-
)
+
5
V
(<
100m
A
)
AG
N
D
RE
S
E
R
V
E
D
R
E
S
E
R
VED
BNC-
jack
IN x
330k
330k
InAmp
+
-
to
ADC
MUX
PGA
G = 1, 2, 4, 8
+
-
GND