DEL HIST

This option deletes all history logs from the analyser. These history logs include failure and maintenance histories, calibration histories and alarm histories. Note that history deletion is prohibited when any type of fault is present. This ensures that faults are fully dealt with and not hidden.

7.2.3 CAL TXD

Some transducer types have functions available only in super calibration mode, which are detailed below.

When entering the CAL TXD menu, a list of valid object types is displayed, which includes those transducer types which are fitted and have super calibration functions associated with them.

The following subsections detail the functions available for these transducer types.

7.2.3.1 GFX

Functions available for GFX transducers are CALIBRATE, READ and SAVE.

CALIBRATE

modifying/inspecting the calibration of the transducer.

It should never be necessary to use either the DEF CAL function or the EDIT CAL function in the field except in the most extreme cases of total data loss.

DEF CAL This option allows the user to perform a complete calibration with gases, to define all points on the absorbance/concentration table for the transducer.

This procedure replaces any existing calibration data with a new set of experimental points, storing the absorption values

corresponding to the stated concentration of a set of test gases which must be supplied to the instrument in turn. Prompts are issued for each pair of values in the order zero, span,

intermediate points. Apart from zero (low) and span (high) the order of entry is immaterial but there must be a minimum of five different intermediate points. Note that immediately the first point is entered all pre-existing data are destroyed

EDIT CAL This option allows the absorbance/concentration table to be edited. This is useful when the table is known for the installed transducer, but it is currently using a different table. It can also be used to alter linearity if necessary.

A simple editor is provided which enables the concentration or absorption co-ordinates of a pre-existing data set to be

modified. It does not allow insertion or deletion of points. The editor can be used to display the data by stepping through it with the ENTER key. Providing nothing is changed, re-calculation of the linearisation function will not take place.

EDIT TC This option allows the temperature compensation coefficients to be edited.There are four such coefficients which provide a linear and a square term correction for sample temperature to both the zero offset and span. The editor can be used to display the data by stepping through it with the ENTER key.

Experimental calibration data is specific to a particular Gfx bench and is therefore stored in the circuitry associated with the individual units. The following functions are provided to transfer data between Gfx benches and the computer in the Xentra chassis:

READ This function imports the configuration of a transducer from the transducer backup memory to the analyser. This configuration includes all factory calibration data, gas name, units and scaling. All data for the transducer in the analyser prior to the read will be lost.

configuration includes all current calibration data, gas name, units and scaling. All data previously in the transducer backup memory will be lost.

7.2.3.2 Ir1520

Functions available for Ir1520 transducers are CALIBRATE, READ and SAVE. These functions are the same as for GFX transducers, with the following exceptions.

Temperature compensation is not performed on Ir1520, so the EDIT TC option is not available.

In the EDIT CAL menu, after all cal points have been edited, a SPAN SIG value is requested.This parameter is used when compensating the live-zero measurement of IR energy for the expected absorption of the lo calibration gas.

7.2.3.3 EXTERNAL INPUT

The purpose of "super calibrating" external inputs is to remove any baseline offset due to tolerances in the input circuitry.

Before eliminating the base offset it is necessary to disconnect any external inputs from PL5/1,2,3,4. The external analogue inputs should be shorted (PL5/1&2,3&4) to ensure 0mA input. The corresponding digital status inputs (PL5/9,10 and 7,8) must be shorted out to ensure that the input channels can be read correctly.

The channel to be calibrated must be selected and the screen will show

E1 BASE OFFSET 167692 OK? Y/N

The number on the display is simply the digitised reading from a zero input and should lie in the range 146,000 - 189,000. If this is not the case and there is a 0mA input on the input terminals then the 04000/924 board is faulty.

When entered the value is stored and used as a zero offset in subsequent scaling calculations.

7.2.4 PARAM

The only parameter that can currently be set using this menu is the flow alarm

FLOW = 37Y/N

The flow of gas through the analyser must be set to the level at which the flow alarm is required to trigger at. The flow value shown will change as the flow changes, and when it is stable, the Y option should be chosen to set the flow alarm trigger point.

7.2.5 EDIT ID

This menu allows the user to change various parameters of the analyser.

These do not affect the operation of the analyser, but are simply a record of the setup. The user can modify the S Number, Model number, serial and order numbers as shown in figure 7.2.

7.2.6 RECONFIGURE

NOTE

This totally reformats the configuration of the instrument.

On selection of this option, all calibration and configuration information will be deleted.

On selection of this option the software will ask twice that the user confirms his intention totally to erase the current system configuration. When selected the screen will go blank for some seconds before the following message is displayed.

"INCOMPATIBLE DATA FORMAT

CONTACT LOCAL SERVOMEX SERVICE"

If a new EEPROM or a new microprocessor PCB with a new EEPROM is fitted then this message will also be displayed, and the instrument will have to be re-configured as follows:

The appearance of this message is entirely normal as there is no longer any useable data stored in the EEPROM. To re-activate the instrument the system will need to be configured by entering the special configuration menu by re-entering the encrypted key sequence (section 7.2.1), the special password (7.2.1b) is not required for this operation.

The Analyser must then be configured as detailed in section 7.3