Metrohm 774 Oven Sample Processor - Manual (Page 31)

3.1 Configuration
774 Oven Sample Processor, Instructions for use 25
3.1.3 Rack definitions
The 774 Oven Sample Processor is supplied with the standard rack for 35
samples. The rack positions for this rack (Rack 1) are already preconfig-
ured. Sample position 36 is reserved for a conditioning beaker.
If different configurations are to be defined for the same type of rack then
the individual racks must be allocated different codes and the stud mag-
nets on the base of each sample rack arranged accordingly.
This means that a particular sample rack can be designated for use with a
particular application and that the use of the wrong rack can be avoided by
the automatic rack code recognition feature.
rack number
Up to 32 different rack configurations can be stored in the sample changer.
rack code
The rack code is used for automatic rack recognition. A particular code can
only be issued once. The standard racks supplied by Metrohm are already
predefined with a code (see page 90). The rack code consists of a 6-place
binary pattern made up of the numbers 0 or 1 which must coincide with the
arrangement of the stud magnets. Number ‘1’ stands for an inserted mag-
net, ‘0’ means that no magnet has been inserted. 63 different codes are
possible (000001 to 111111).
Magnet inserted
In this
example the code is:
000110
base of rack
rack type
The rack type indicates an internal table of positions, in which the angles of
rotation of the beaker positions are defined. Metrohm racks use the follow-
ing type name pattern:
MXX-Y (XX = number of sample beakers, Y = special code: 0 for 1-row,
1 for 2-row and 2 for 3-row standard racks)
e.g. M36-0 is a 1-row Metrohm standard rack with 36 sample positions.
work position
The correct setting of the working position is very important. This is the lift
height which is to be used with the corresponding sample rack. It should be
selected so that the working head is standing in the optimal position. The
working position is given in mm (from the upper stop position).
A convenient way of determining this position is to set the required height
manually (normal state) with the <Ð> and <Ï> keys. This is done by
placing a sealed sample vessel on the oven and moving the lift carefully
downwards until the needle penetrates the septum and the lower rim of the
septum closure coincides with the upper rim of the oven opening.
The keyboard can then be used to open the configuration menu and the
current lift position in the display can be accepted in the menu entry 'work
position' with the <CLEAR> key.