PyVisa Tango Class User‘s Guide

PyVisa Tango Python Class

Contents :

PyVisa Class Identification :

PyVisa Class Inheritance :

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Tango::DeviceImpl

PyVisa

PyVisa Class Description :

PyVisa Properties :

There is no class properties

Device Properties
Name	Description	Type	Default Value
VisaName	The name of the device understood by the VISA library	String	SetMePlease

PyVisa Class Commands
Name	Input type	Output type	Level	Description
State	DEV_VOID	DEV_STATE	OPERATOR	This command gets the device state (stored in its device_state data member) and returns it to the caller.
Status	DEV_VOID	CONST_DEV_STRING	OPERATOR	This command gets the device status (stored in its device_status data member) and returns it to the caller.
Open	DEV_VOID	DEV_VOID	OPERATOR	Open the VISA device
Close	DEV_VOID	DEV_VOID	OPERATOR	Close the VISA device
Write	DEVVAR_CHARARRAY	DEV_VOID	OPERATOR	Write a string to the VISA device
Read	DEV_USHORT	DEVVAR_CHARARRAY	OPERATOR	Read the given amount of characters.
ReadLine	DEV_VOID	DEVVAR_CHARARRAY	OPERATOR	Read data until the end
ReadValues	DEV_VOID	DEVVAR_FLOATARRAY	OPERATOR	Perform a read command and parses the result finding the different values. It uses the ValuesFormat attribute. If you want to use another format for a specific answer, please, set the ValuesFormat before. Possible formats are: ascii (default), singe, double
Ask	DEVVAR_CHARARRAY	DEVVAR_CHARARRAY	OPERATOR	Perform a write command and return the answer from the device.
AskValues	DEVVAR_CHARARRAY	DEVVAR_FLOATARRAY	OPERATOR	Perform a write command and return the answer from the device parsed to have a list of values using the attribute ValuesFormat. If you want to use another format for a specific answer, please, set the ValuesFormat before. Possible formats are: ascii (default), singe, double
Reset	DEV_VOID	DEV_VOID	OPERATOR	Performs a reset to the device
Trigger	DEV_VOID	DEV_VOID	OPERATOR	Send a trigger signal to the device

Command State :

device_state

State Definition
Input Argument	Tango::DEV_VOID	none.
Output Argument	Tango::DEV_STATE	State Code
DisplayLevel	OPERATOR	..
Inherited	true	..
Abstract	true	..
Polling Period	Not polled	..

Command allowed for	All states	..

Command Status :

device_status

Status Definition
Input Argument	Tango::DEV_VOID	none.
Output Argument	Tango::CONST_DEV_STRING	Status description
DisplayLevel	OPERATOR	..
Inherited	true	..
Abstract	true	..
Polling Period	Not polled	..

Command allowed for	All states	..

Command Open :

Open the VISA device

Open Definition
Input Argument	Tango::DEV_VOID
Output Argument	Tango::DEV_VOID
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	ON FAULT	..

Command Close :

Close the VISA device

Close Definition
Input Argument	Tango::DEV_VOID
Output Argument	Tango::DEV_VOID
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	OFF	..

Command Write :

Write Definition
Input Argument	Tango::DEVVAR_CHARARRAY	Command string
Output Argument	Tango::DEV_VOID
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command Read :

Read Definition
Input Argument	Tango::DEV_USHORT	Characters to read
Output Argument	Tango::DEVVAR_CHARARRAY	Characters readed
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command ReadLine :

ReadLine Definition
Input Argument	Tango::DEV_VOID
Output Argument	Tango::DEVVAR_CHARARRAY	Characters readed
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command ReadValues :

ReadValues Definition
Input Argument	Tango::DEV_VOID
Output Argument	Tango::DEVVAR_FLOATARRAY	List of values read
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command Ask :

Ask Definition
Input Argument	Tango::DEVVAR_CHARARRAY	Command to write
Output Argument	Tango::DEVVAR_CHARARRAY	Answer from the device
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command AskValues :

AskValues Definition
Input Argument	Tango::DEVVAR_CHARARRAY	Command to write
Output Argument	Tango::DEVVAR_FLOATARRAY	List of values
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command Reset :

Performs a reset to the device

Reset Definition
Input Argument	Tango::DEV_VOID
Output Argument	Tango::DEV_VOID
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

Command Trigger :

Send a trigger signal to the device

Trigger Definition
Input Argument	Tango::DEV_VOID
Output Argument	Tango::DEV_VOID
DisplayLevel	OPERATOR	..
Inherited	false	..
Abstract	false	..
Polling Period	Not polled	..

Command NOT allowed for	FAULT OFF	..

PyVisa Class Attributes
Name	Inherited	Abstract	Attr. type	R/W type	Data type	Level	Description
Timeout	false	false	Scalar	READ_WRITE	Tango::DEV_FLOAT	OPERATOR	Timeout in seconds for all device operations\nDefault value is 5 and you can set it to 0 for\nnon-blocking mode.\nNote that your local VISA library may round up this\nvalue heavily. I experienced this effect with my\nNational Instruments VISA implementation,\nwhich rounds off to 0, 1, 3 and 10 seconds.
ChunkSize	false	false	Scalar	READ_WRITE	Tango::DEV_SHORT	OPERATOR	Length of read data chunks in bytes\nDefault value is 20kb
ValuesFormat	false	false	Scalar	READ_WRITE	Tango::DEV_STRING	OPERATOR	Data format for lists of read values\n+) ASCII (the default)\n+) SINGLE\n+) DOUBLE\n+) BIG_ENDIAN\n\nThis attribute is useful with the\nReadValues and AskForValues commands
TermChars	false	false	Scalar	READ_WRITE	Tango::DEV_STRING	OPERATOR	The termination characters for each read and write operation.\nNone (Default)\n\r (CR)\n\ n (LF)\n\nor any combination
SendEnd	false	false	Scalar	READ_WRITE	Tango::DEV_BOOLEAN	OPERATOR	whether to assert END after each write operation\nDefault value is True
Delay	false	false	Scalar	READ_WRITE	Tango::DEV_FLOAT	OPERATOR	Delay time to wait after each write operation\nDefault is 0

There is no dynamic attribute defined.

Attribute Timeout :

Timeout in seconds for all device operations\nDefault value is 5 and you can set it to 0 for\nnon-blocking mode.\nNote that your local VISA library may round up this\nvalue heavily. I experienced this effect with my\nNational Instruments VISA implementation,\nwhich rounds off to 0, 1, 3 and 10 seconds.

Attribute Definition
Attribute Type	Scalar
R/W Type	READ_WRITE
Data Type	Tango::DEV_FLOAT
Display Level	OPERATOR
Inherited	false
Abstract	false
Polling Period	Not polled
Memorized	true
Write hardware at init.	true

Read allowed for	All states
Write allowed for	All states

Attribute Properties
label	Timeout
unit
standard unit
display unit
format
max_value
min_value	0
max_alarm
min_alarm
max_warning
min_warning
delta_time
delta_val

Attribute Event Criteria
Periodic	Not set
Relative Change	Not set
Absolute Change	Not set

Archive Periodic	Not set
Archive Relative Change	Not set
Archive Absolute Change	Not set

Push Change event by user code	false

Push Archive event by user code	false

Push DataReady event by user code	Not set

Attribute ChunkSize :

Length of read data chunks in bytes\nDefault value is 20kb

Attribute Definition
Attribute Type	Scalar
R/W Type	READ_WRITE
Data Type	Tango::DEV_SHORT
Display Level	OPERATOR
Inherited	false
Abstract	false
Polling Period	Not polled
Memorized	true
Write hardware at init.	true

Read allowed for	All states
Write allowed for	All states

Attribute Properties
label	ChunkSize
unit
standard unit
display unit
format
max_value
min_value
max_alarm
min_alarm
max_warning
min_warning
delta_time
delta_val

Attribute Event Criteria
Periodic	Not set
Relative Change	Not set
Absolute Change	Not set

Archive Periodic	Not set
Archive Relative Change	Not set
Archive Absolute Change	Not set

Push Change event by user code	false

Push Archive event by user code	false

Push DataReady event by user code	Not set

Attribute ValuesFormat :

Data format for lists of read values\n+) ASCII (the default)\n+) SINGLE\n+) DOUBLE\n+) BIG_ENDIAN\n\nThis attribute is useful with the\nReadValues and AskForValues commands

Attribute Definition
Attribute Type	Scalar
R/W Type	READ_WRITE
Data Type	Tango::DEV_STRING
Display Level	OPERATOR
Inherited	false
Abstract	false
Polling Period	Not polled
Memorized	true
Write hardware at init.	true

Read allowed for	All states
Write allowed for	All states

Attribute Properties
label	ValuesFormat
unit
standard unit
display unit
format
max_value
min_value
max_alarm
min_alarm
max_warning
min_warning
delta_time
delta_val

Attribute Event Criteria
Periodic	Not set
Relative Change	Not set
Absolute Change	Not set

Archive Periodic	Not set
Archive Relative Change	Not set
Archive Absolute Change	Not set

Push Change event by user code	false

Push Archive event by user code	false

Push DataReady event by user code	Not set

Attribute TermChars :

The termination characters for each read and write operation.\nNone (Default)\n\r (CR)\n\ n (LF)\n\nor any combination

Attribute Definition
Attribute Type	Scalar
R/W Type	READ_WRITE
Data Type	Tango::DEV_STRING
Display Level	OPERATOR
Inherited	false
Abstract	false
Polling Period	Not polled
Memorized	true
Write hardware at init.	true

Read allowed for	All states
Write allowed for	All states

Attribute Properties
label	TermChars
unit
standard unit
display unit
format
max_value
min_value
max_alarm
min_alarm
max_warning
min_warning
delta_time
delta_val

Attribute Event Criteria
Periodic	Not set
Relative Change	Not set
Absolute Change	Not set

Archive Periodic	Not set
Archive Relative Change	Not set
Archive Absolute Change	Not set

Push Change event by user code	false

Push Archive event by user code	false

Push DataReady event by user code	Not set

Attribute SendEnd :

whether to assert END after each write operation\nDefault value is True

Attribute Definition
Attribute Type	Scalar
R/W Type	READ_WRITE
Data Type	Tango::DEV_BOOLEAN
Display Level	OPERATOR
Inherited	false
Abstract	false
Polling Period	Not polled
Memorized	true
Write hardware at init.	true

Read allowed for	All states
Write allowed for	All states

Attribute Properties
label	SendEnd
unit
standard unit
display unit
format
max_value
min_value
max_alarm
min_alarm
max_warning
min_warning
delta_time
delta_val

Attribute Event Criteria
Periodic	Not set
Relative Change	Not set
Absolute Change	Not set

Archive Periodic	Not set
Archive Relative Change	Not set
Archive Absolute Change	Not set

Push Change event by user code	false

Push Archive event by user code	false

Push DataReady event by user code	Not set

Attribute Delay :

Delay time to wait after each write operation\nDefault is 0

Attribute Definition
Attribute Type	Scalar
R/W Type	READ_WRITE
Data Type	Tango::DEV_FLOAT
Display Level	OPERATOR
Inherited	false
Abstract	false
Polling Period	Not polled
Memorized	true
Write hardware at init.	true

Read allowed for	All states
Write allowed for	All states

Attribute Properties
label	Delay
unit
standard unit
display unit
format
max_value
min_value	0
max_alarm
min_alarm
max_warning
min_warning
delta_time
delta_val

Attribute Event Criteria
Periodic	Not set
Relative Change	Not set
Absolute Change	Not set

Archive Periodic	Not set
Archive Relative Change	Not set
Archive Absolute Change	Not set

Push Change event by user code	false

Push Archive event by user code	false

Push DataReady event by user code	Not set

PyVisa Class States
Name	Description
ON	Device is Open (By default)
FAULT	The device is in some fault state
OFF	The device is OFF.