Technical Manual
Page 19
CODEL
OPS.109
Issue : B
Rev. : 1
Date : 23/10/13
Doc. i/d : 0109/6
Ref. : 090028
7. DDU Operation
7.1. Introduction
After the instrument has been commissioned it will measure the flow velocity between the two transducers and
produce an output proportional to gas velocity. An integral 32-character display shows the calculated levels.
The instrument allows the operator to interrogate the microprocessor to observe the system parameters and to
change them if required.
A menu-based program is used, accessed being gained by four keys mounted on the cover of the signal
processor.
The DDU communicates serially with the SPU; for successful communications to take place the DDU and SPU
serial addresses must be the same:
-
serial comms. address
– DDU microprocessor card rotary switch – SW1
-
serial comms. address
– SPU microprocessor card rotary switch – SW1 (SW2 = 0)
7.2. Operating Modes
The instrument has four modes of operation that are identified by a number in the top left hand corner of the
display.
1.
Operating Mode
- displays measured parameters.
2.
Parameter Mode
- displays operating parameters.
3.
Normalisation Mode
- not applicable.
4.
Diagnostic Mode
- investigates instrument operation. Self-checks are continually made by the
instrument; should a complication exist the fault will be shown on the fault status display.
5.
Set-up Mode
- sets operating parameters. The operating parameters must be entered for the
instrument to function correctly. This mode can only be accessed using the security code.
Figure 12 : Illustration of the Processor Display & Keys
Back-Lit LCD Display
Alarm LED
UP/DOWN Arrow keys
Data Valid LED
Mode Key
Enter Key