Instrument drivers
The instrument drivers in pymanip are directly those of fluidlab.instruments.
An instance object represents an actual physical instrument, and the features that can be
read or set are represented as instance attributes. These attributes have consistant names
for all our instrument drivers, summarized in the table below
Physical measurement |
Attribute name |
|---|---|
DC Voltage |
vdc |
AC Voltage |
vrms |
DC Current |
idc |
AC Current |
irms |
2-wire impedence |
ohm |
4-wire impedence |
ohm_4w |
Signal phase shift |
angle |
Frequency |
freq |
On Off switch |
onoff |
Pressure |
pressure |
Temperature |
temperature |
Setpoint |
setpoint |
Some device may have specific feature name in special cases, but we try to keep using similar
names for similar features.
Each feature then can be accessed by get() and set() methods, as appropriate. The
get() will query the instrument for the value. The set() method will set the value.
It is a design choice to use getters and setters, instead of python properties, to make the
actual communication command more explicit.
For example to read a voltage on a multimeter:
Vdc = multimeter.vdc.get()
And to set the voltage setpoint to 1 volt on a power supply:
powersupply.vdc.set(1.0)
Unless otherwise specified, vdc.get() will always read an actual voltage, and not
the voltage setpoint. This is a design choice because we think the users should know what setpoint
they have set in the general case. In case it is necessary to actually query the instrument for
its setpoint, an additionnal setpoint attribute may be defined.
The implementation details of the instrument drivers, and how they are mixed with the interface
and feature classes is described in the fluidlab.instruments module documentation.
pymanip.instruments defines shortcut classes, as well as an asynchronous extension to
the fluidlab.instruments classes.