• Compensating measured values, e.g. cross sensitivity
correction
• Controlling system functions, e.g. calibration
• Display and control functions
• Controlling associated systems, e.g. gas supply
• Communicating with external systems
The system controller communicates with the other functional
units of the gas analyzer (e.g. the analyzer modules) via the
system bus.
Interfaces for controlling associated systems and for communicating
with external systems are located on the system controller
(Ethernet 10/100/1000BASE-T interface) and on the I/O modules.
The I/O modules are attached and directly connected to the
system controller board. There are various types of I/O modules:
• 2-way analog output modules have two analog outputs.
• 4-way analog output modules have four analog outputs.
• 4-way analog input modules have four analog inputs.
• Digital I/O modules have four digital inputs and four digital
outputs.
• Modbus modules have one RS485 and one RS232 interface.
• Profibus modules have one RS485 and one MBP interface
(not intrinsically safe).
Examples of I/O module applications include:
• Output of measured values
• Output of status and alarm signals
• Calibration control
• Control of external solenoid valves and pumps
• Measurement range switching and feedback
• Feed of current or status signals from external analyzers
• Feed of status signals from peripherals