SENTRON A120-001, Technical Manual

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4
Electrical connections
The diagram below illustrates how the components of the pH-kit are connected together. The
modules will only function when connected in this order.
1. ISFET
Reference electrode
2. Analog front-end 3. AD Converter
(Optional)
4. USB Interface
(Optional)

Modules 1 and 2 are always needed to conduct pH measurements with the test kit. Modules
3 and 4 are optional.
3.1 Analog front-end module
The ISFET sensor is connected to the Analog Front-End module through an FFC connector. There are
also 7 pin connections on the module. One pin (Pin 7) is for connection of the reference electrode.
The remaining 6 serve as output pins for the Analog front-end module. They are described below:
7
.

Pin 1. pH signal out ~52 mV/pH. pH 7 between 500 and 1800 mV
Pin 2. +3V3 Power +3V3 DC power power input +/- 100mV
Pin 3. AGND Analog Ground
Pin 4. PT1000 Directly wired to the PT1000
Pin 5. PT1000 Directly wired to the PT1000
Pin 6. N.C. Not used
Pin 7. Reference External reference electrode connection
3.2 AD Converter module
The 6 pin connector of the AD Converter module can be attached directly to the Analog Front-end
module. The AD Converter module also had 4 output pins, which are described below:








Pin 1. +5V +5V DC power input +/- 100mV
Pin 2. RxD Data input, TTL 5V level, 115k2, 8N1
Pin 3. TxD Data output, TTL 5V level, 115k2, 8N1
Pin 4. GND Digital GND.
The AD Converter module contains 1.5kV galvanic insulation between inputs and outputs.
1.

2.
3.

4.

1.

2.
3.

4.

5.

6.
ISFET
sensor
connector
Analog
front-end
connector
