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TOF-MS Logic Controller

Front view of spectrometer control unit

The TOF-MS Logic Controller is particularly useful when building systems where both simple manual control and computer control is required. There are two modules:

  1. A logic board provides a central place from which to control the enabling of the system high voltages and the polarity of all supplies. The logic includes a simple timing sequence in response to a request for polarity changeover that disables the high voltages, pauses, changes the polarity, pauses, and re-enables the high voltages. Thus in a manual system, the polarity of the whole spectrometer may be changed with a single switch. Similarly all high voltages can be disabled from a single point, which simplifies safe operation and protection of the system from vacuum accident or other events that require interlocks. If the system is to be computer controlled, then in principle the computer could be made responsible for controlling each high voltage unit separately and for the polarity changeover sequence. However, many designers still prefer to have safety interlocks implemented in hardware , particularly whist software is still under development. And in any case by centralising the high voltage and polarity control the computer interface need consist only of two TTL signals.

  2. A second board provides drive for an octopole set of deflector electrodes, such as those provided in the Kore extraction optics. Control is either via front panel potentiometers or via analogue inputs at the back panel. Two sets of front panel controls are provided, the appropriate pair being selected by means of a polarity signal from the polarity control board.

Rear view of spectrometer control unit

There are a total of eight 9 pin miniature 'D' type plugs provided to output polarity and high voltage enable control to other units in the system. Although they each have specific labels and are wired as described below, it is important to realise that the intent of the design is that these can be used for general purposes. Each of the two logical signals, high voltage enable/disable and negative/positive polarity, has been assigned three double pole changeover relays on the internal PCB. The normally open and normally closed contacts can be easily patched to ground or +5 Volts, or indeed anything else that seems appropriate. External supplies might have a range of conventions for switching polarity or for high voltage enable. For example TTL signal levels, the shorting of a connection to ground or the making of a link. The idea is that any of these conventions can be accommodated by a suitable wiring of one of the sets of relay contacts.


Last updated: Thursday, September 15, 2005, 11:33

© Kore Technology Limited 2005