GDU
27-1500
Original Instructions
7
9901X0265 Issue 2
Only connect the equipment to a polarised earthed power socket.
Ne branchez l'équipement
qu’à une prise de courant mise à la terre polarisée.
Switch off and unplug the equipment before cleaning.
Eteignez et débranchez l'équipement avant de le nettoyer.
1.5
The GDU Operating System
The GDU Data acquisition Operating System (GDOS) is the GDU control software that
runs in the GDU’s CPU. It is able to interpret the English-like commands (GDOS
commands) sent from a computer. These GDOS commands are used to configure the
GDU for data acquisition and control and additionally may be used to interrogate the
operating conditions of the GDU and recall logged data. Refer to the GDU Technical
Manual for details on the command syntax.
1.5.1 CPU Module
The GDU mainframe accepts one CPU module with its RS232 and Ethernet interfaces.
The module contains a microprocessor with the GDU operating system GDOS. The on-
board clock provides a 24 hour clock and calendar. It resides in the 5
th
slot to the far
right-hand side of the chassis. It should not be inserted in any other positions. The
Ethernet interface should only be connected to a host PC via an appropriate router.
1.5.2 Analogue Input Module
The GDU mainframe has four slots (slots 1 to 4) which can accept the analogue input
modules. The system can address up to 32 individual input channels where one
channel normally corresponds to one analogue input.
Each input module accepts up to eight analogue inputs. It also has a dedicated
analogue to digital converter (ADC) that converts the analogue input signal to digital
data. This data is transferred to the CPU for processing by the GDU system. Each
module also contains a precision instrumentation amplifier with 11 programmable gain
ranges (x1 to x1024).
After amplification any transducer signal offset can be optionally removed by the on-
board voltage generator, and the resulting signal digitised.
The GDU input module covers a wide range of transducer types. Full details are given
in sections 3 and 4. The following is a brief description of the facilities available.
The range provides for the connections of differential and single ended voltage
sources, with sensitivities ranging from +/-5V full scale to +/-10mV full scale. A 10V
supply is available for those sensors requiring excitation such as pressure transducers
and L
VDT’s.
