This machine is loosely modeled on a gas chromatograph, and analyzes the contents of the currently selected creature’s bloodstream. Switch it on using the black knob on the left, which can also be used to select various modes.
In the first mode, the main display shows the chromatogram of the blood, on which are superimposed the characteristic signatures of the three chemicals currently selected for monitoring. There’s nothing much to learn from this mode – it’s just for show. The second mode displays a graph over time of the concentrations of these chemicals, and the third mode enables an alarm (see below).
The main panel contains three “channels”. Each one monitors a particular chemical, whose formula is selected using the bottom knob. As well as the graphical display, the concentration of this chemical is shown on the meter.
By default, the meter (and graph) shows the concentration from zero to fully saturated. However, the upper and lower limits can be controlled using the MIN and MAX knobs. As you turn these knobs, their values are reflected in the meter, to make it easier to judge. When MIN is higher than zero, and/or MAX is lower than 1, the meter and graph have this range, so a meter reading of zero means MIN or less. You can use the max and min knobs to “zoom in” on a particular part of the concentration range, making it easier to see subtle changes in concentration.
By turning the black knob to ALARM, the machine will emit a warning when any of the three chemicals exceed the MIN or MAX values. For example, if you’re worried that a creature is not getting enough to eat, you might select GLY (glycogen) as one of the chemicals and set MIN to around 0.2. If the creature gets seriously low in glycogen the alarm will sound.
Note: There’s a handy reference list of the current chemical names and meanings on the lab pinboard.