Peter M. Groen / libmodbus

Signed-off-by: Stéphane Raimbault <stephane.raimbault@gmail.com>

This replaces the lengthy license text headers with a short
and standardized license tag. See http://spdx.org for details.

This is useful e.g. for license compliance tools which scan
through files and generate a report of the licenses used
in a project.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

It concerns only the files in 'tests' directory.

Thanks again to Stefan Finzel.
It would be nice to run Valgrind more often...

The function name was confusing because the write operation is performed
before the read. Take care to swap the arguments in the migration process.

Related to 49d6f4a71f686de64e5c28d6dd8acd2c98c5038d.

modbus_set_slave must be used to set the slave ID of the remote
device to talk in master mode and to set the internal slave ID in
slave mode.

If you talk to several devices, you need to call modbus_set_slave
each time the following requests must be sent to another device.