4.2 Sections

As you already have seen in the example above, an EDL script consists of one or more sections. There are up to 6 different types of sections. These are specified by the following section keywords:

DEVICES
VARIABLES
ASSIGNMENTS
PHASES
PREPARATIONS
EXPERIMENT

Please note that the section keywords always have to be followed by a colon, :.

The first and last two sections have already been used in our example script: The DEVICES section consists simply of a list of all the devices that will be used in the experiment (or at least the ones that are going to be controlled by the computer).

The VARIABLES section for declaring and initializing variables has also already been discussed in the example.

Because pulses play an important role in modern EPR experiments lots of elements for handling pulses and the pulsers that creates them are built into fsc2. Thus, there are even two special sections, ASSIGNMENTS and PHASES, exclusively devoted to the pulser setup. The basic setup of the pulser (e.g. setting the timebase and trigger mode as well as setting up the pulser channels) is done in the ASSIGNMENTS section while the PHASES section is all about phase-cycling - here you may have to define the phase sequences to be used in the experiment as well as the way the resulting echos will be added up. Because this is a rather extensive subject (and because of the different ways pulsers are used in the supported spectrometers) an in-depth discussion of both these sections is part of a whole chapter (see Using Pulsers).

As you already have seen, the PREPARATIONS section is for setting up all the other devices and initializing graphics - basically the things you would do before actually starting an experiment. This is also the section where pulses are going to be defined. Again, for more details about this last topic see the chapter about pulse generators and pulses (see Using Pulsers).

Finally, there is the EXPERIMENT section. As you already have seen this section usually consists of one or more loops, possibly nested, where data are acquired and stored.

While the sections of an EDL script don't have to appear in the sequence in which they are listed above it is probably best not to experiment too much with this. In any case, if it exists the EXPERIMENT section must always be the last one.

All the section keywords can be abbreviated, here's the complete list of valid section keywords:

• DEVICES, or DEV, DEVS, DEVICE
• VARIABLES, or VAR, VARS, VARIABLE
• ASSIGNMENTS, or ASS, ASSIGNMENT
• PHASES, or PHA, PHAS, PHASE
• PREPARATIONS, or PREP, PREPS, PREPARATION
• EXPERIMENT, or EXP

Beside these sections there is a label that looks very similar to a section label, the

• ON_STOP

label (which also must be followed by a colon, :). It can only appear within the EXPERIMENT section. The ON_STOP label can be used to guarantee that a certain part of the EXPERIMENT section is going to be executed even after the user hit the Stop button. It will probably contain code that stores previously unsaved data and does other things that are necessary before the experiment really is finished. When fsc2 executes the code following the ON_STOP label it won't react to the Stop button anymore.

This document was generated by Jens Thoms Toerring on September 6, 2017 using texi2html 1.82.