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Online documentation - Differences in version 0.74
GPIB
Version 0.74 does not support adding user-defined compute functions, but they can still be added by directly modifying /usr/share/mezurit2/script.py.
The GPIB_Device class takes slightly different arguments and is also not directly callable.
Instead, one must store its return value in an intermediate variable, then define a channel function which calls the self.read method.
In addition, a call to self.reset must be added to reset_gpib() (in newer versions this happens automatically).
The modified syntax is described below, along with an example:
GPIB_Device (read_period, intro_str, read_str, reply_fmt, write_fmt)
| read_period | float | Time between updates in seconds |
| intro_str | str | GPIB command needed to query the model name (normally "*IDN?") |
| read_str | str | GPIB command needed to get (read) the parameter |
| reply_fmt | str | C printf-style format needed to convert a reply to a floating point value |
| write_fmt | str | C printf-style format needed to set the parameter (supply empty string if N/A) |
| return value | | Instance of the GPIB_Device class |
Example: Agilent signal generator
| Code: |
Agilent_8648_FREQ = GPIB_Device(0.5, "*IDN?", "FREQ:CW?", "%lf", "FREQ:CW %1.8le HZ")
def A8648_Freq (brd, pad) : return Agilent_8648_FREQ.read(brd, pad)
def reset_gpib () :
Agilent_8648_FREQ.reset()
... |
| Channel def.: |
X1 (MHz) = A8648_Freq(0, 18) |
| Result: |
During the parse phase Mezurit 2 will create a gpib slot for board 0, address 18.
In panel mode it will query the device with the command "FREQ:CW?" every 0.5 seconds and decode the reply (e.g. "1.000000E+8") as a floating point value 100e6 (displayed as 100 MHz).
If the user were to set X1 to some value (e.g. 95 MHz), Mezurit 2 would immediately send "FREQ:CW 9.500000E+7 HZ" to the instrument, then resume reading every 0.5 seconds. |
The parameters self.inverse_fn and self.noninverse_fn are not present in version 0.74.
However, the functionality of the latter can be obtained by placing the desired expression in the channel function, as is done for SR830_SensIn() in /usr/share/mezurit2/script.py.
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