Siemens Maxum II Manual page 16

System Functions
3.3 Analyzer Operation
Electronic Pressure Control
The carrier gas pressure that is used to push the sample through the columns is controlled by
an Electronic Pressure Control Module (EPCM) or in some applications by mechanical
regulators. The EPCM is mounted on manifolds located on the EC right-side wall. The EPCM
pneumatics are digitally controlled by the Sensor Near Electronics (SNE) software module. Up
to four EPCMs can be mounted in an EC. Each EPCM contains two channels, and each
channel can use a different gas at a different pressure. EPCMs are also used to control the
fuels for some of the detector modules. Each Electronic Pressure Control Module (EPCM)
communicates the actual pressure back to the SNE software module. Information may then
be displayed on the Maintenance Panel. Depending on model and application, up to 3 or 4
EPCMs may be installed
Oven Heaters
For the columns and detectors to work correctly, they must usually be operated at elevated
temperatures. The Maxum II uses electrical heater(s) to elevate the temperature. These
heaters (not shown in block diagram) are connected to relays in the electronics compartment
and, like the valves and the Electronic Pressure Control Modules, are controlled by the SNE
software module.
Detector
The sample eluted from the columns is transported to the associated detector that senses the
presence of the sample and converts it to an electrical signal. Depending upon the application,
the Maxum II can include up to three detector modules. Each detector module can have
multiple detector sensor elements. Several detector module types are available including
Thermistor, Filament, Flame Ionization, Flame Photometric, and Pulsed Discharge. The
resulting electrical signal from the detector is then connected to the Detector Personality
Module (DPM) located in the EC.
Sensor Near Electronics (SNE) Software Module
The detector signal(s) is routed to the Detector Personality Module (DPM). The DPM (unique
for each detector type) amplifies the analog signal and converts it to a digital signal. The digital
signal output from the DPM is processed by the SNE software module. The DPM is interfaced
to installed peripherals connected to the I
commands. All accessible I/O's are uniquely addressable through the module type, enclosure
ID, SNE, location ID and module channel number.
In earlier analyzers, the SNE control and processing functions were performed by a separate
processor board, called the SNE controller (SNECON) mounted in the DPM cage assembly
and connected to the SYSCON by an Ethernet cable.
System Controller (SYSCON)
The System Controller (SYSCON) resides in a pullout drop-down assembly located in the EC
and controls all external communications and internal communication. The SYSCON houses
the primary processor, plug-in I/O boards (for external signal control), communication
interfaces, and an interface to the maintenance panel display. All internal communication
between modules and SYSCON is via the internal I
16
C bus through a set of digital and analog I/O signal
2
C signal bus.
2
Maxum edition II Analyzer General Maintenance
Manual, August 2018, A5E42019842001