herosdevices.core.bus.visa

Primitive functions and classes representing visa connections.

Module Contents

herosdevices.core.bus.visa.pyvisa = None

herosdevices.core.bus.visa.usb = None

class herosdevices.core.bus.visa.VisaConnection(resource: str, keep_alive: bool = True, **kwargs)

A class to manage VISA communication connections.

This class provides functionality to handle visa connections including opening/closing connections, reading data, and writing data.

Parameters:

• resource – The resource name of the visa instrument (e.g. TCPIP::my_device_hostname::INSTR).

• keep_alive – Flag indicating whether to keep the connection open between operations.

• **kwargs – Keyword arguments passed to pyvisa.open_resource

resource: str

connection: pyvisa.resources.MessageBasedResource | None = None

keep_alive = True

operation() → collections.abc.Iterator[None]

Context manager for handling visa connection operations.

Ensures the visa connection is open before performing operations and closes it afterward if self.keep_alive is False.

Yields:

Yields control back to the caller for performing operations within the context.

close() → None

Close the visa connection if it is open.

The connection is reopened automatically on the next read or write operation.

goto_local() → None

Set the device back to local mode by sending the USB488 GO_TO_LOCAL request.

pyvisa-py asserts the remote enable line of USBTMC devices when opening a connection but never releases it, leaving the device in remote mode (e.g. with a locked front panel) even after the connection is closed. Sending this request sets the device back to local mode.

This is a no-op if the connection is not a pyvisa-py USBTMC connection whose device supports the request. Errors are logged instead of raised, as this is a best effort cleanup operation.

read() → str | None

Do device read query.

Returns:

The decoded data as string, or None if an error occurs.

write(message: str, read_echo: bool = False, *args, **kwargs) → str | None

Write to the visa connection.

Parameters:

• message – The message to be written to the serial connection.

• read_echo – If True, reads back the echo after writing. Defaults to False.