Metrohm 838 Advanced Sample Processor Manual - Manual (Page 73)

3.1 Sample racks
Metrohm 838 Advanced Sample Processor, Appendix 65
3.1.2 Magnet codes
Each individual sample rack can be identified unambiguously by a
magnet code. Magnet pins attached to the base of the rack can be ar-
ranged to form a 6-place binary code. The Sample Processor can then
automatically recognize which rack has been placed on it if the rack is
located at the starting position after initialization.
When a rack is changed it should first be brought to the starting posi-
tion by pressing the <RACK> key. In this way the rack can be posi-
tively recognized, which makes correct beaker positioning possible.
Each type of rack is assigned to an internal position table, in which the
angle of rotation and distance to the center of the rack is defined for
each rack position.
When a sample series is started the Sample Processor automatically
moves the rack to the starting position so that its magnet code can be
read off. This ensures that the beaker positions coincide with the inter-
nal position table of the current rack.
The standard racks supplied by Metrohm are already provided with a
predefined magnet code for each type of rack. If several racks of the
same type are in use then the magnet pins can be arranged differently
to allow the unambiguous identification of each individual rack.
Magnet code format (examples):
000001 i.e. only one magnet inserted, Bit 0
000101 i.e. two magnets inserted, Bit 0 and 2
63 different combinations are possible. Code 000000 stands for "no de-
fined code".
3.1.3 Rack data
In many applications the method and beaker sizes must be observed
exactly. As sample racks are intended for particular beaker sizes, the
rack definitions also contain, in addition to the rack positions them-
selves, data about the lift positions that are directly associated with the
particular beaker size.
The following data can be defined for each rack:
Rack name
Unambiguous identification, ordering
number is standard
Code Magnet code for automatic rack rec-
ognition
Work position Working height for Lift 1 and 2 *
Rinse position Rinsing height for Lift 1 and 2 *
Shift position Shifting height for Lift 1 and 2 *
Special position Additional height for Lift 1 and 2 *
Beaker radius Radius of sample beaker
Beaker sensor Beaker checking mode