SENTRON A120-001, Technical Manual

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Description
Sentron offers a glass-free modular pH-kit designed specifically for development and testing
purposes. With this pH-kit, development engineers and researchers have a large degree of flexibility
in how they integrate our proprietary ISFET pH sensor into their applications or experimental set-ups.
Due to the modular design, the functionality can be expanded as required and components can be
replaced individually.
The pH-kit consist of a ISFET pH sensor, Reference and Analog front-end module. These modules are
always needed as a basis for pH measurement. Thanks to the small size of the ISFET pH sensor and
Reference electrode it can be used to measure small volumes or develop applications with small
form factors. The Analog Front-end module has an uncalibrated analog pH output signal with a
voltage output 0 — 3.3 V of ~ 52 mV / pH and pH 7 between 500 mV and 1800 mV. The PT1000 RDT
temperature sensor in the ISFET pH sensor is wired directly to the Analog front-end module output.
The reference electrode also connects to the Analog front-end module and either the standard
reference electrode with porous PTFE diaphragm can be used or a suitable custom reference
electrode can be attached.
The AD Converter module can be attached to the Analog front-end module. This extension module
with microprocessor, AD Converter and galvanic isolation makes it well suited for use in embedded
applications. The communication with the AD Converter is based on a serial RS232 interface with a
TTL level. Using a standard serial interface it is possible to perform calibrations and read pH and
temperature values. Application of a temperature correction algorithm to the pH signal is performed
directly by the microcontroller of the AD Converter module. The galvanic isolation provides an extra
safety barrier and prevents ground loops.
With the USB Interface extension module, which connects to the AD Converter module, it is possible
to request measured pH and temperature values from a laptop or PC with a USB port. The USB
Interface extension module, with appropriate user developed software, allows the pH-kit to be used
for applications that require direct connection to a PC, such as real time monitoring of pH values in
an experiment or process.