Write to a serial instrument

[clavay]

Hi,

I have an issue to send a write with a serial instrument. (robot to make it move)

When I try this it works : import serial ser = serial.Serial(port='/dev/ttyS0', baudrate=9600, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, bytesize=serial.EIGHTBITS) ser.write('B+100') ser.close() -> The robot moves.

But this doesn't work : import visa rm = visa.ResourceManager('@py') list = rm.list_resources() my_inst = rm.open_resource(list[0], baud_rate=9600, data_bits=8, parity=visa.constants.Parity.none, stop_bits=visa.constants.StopBits.one) my_inst.write('B+100')

-> I have this output : (7, <StatusCode.success: 0>) -> and list say : (u'ASRL/dev/ttyS0::INSTR',) -> But nothing append.

python -m visa info : Machine Details: Platform ID: Linux-4.9.0-6-amd64-x86_64-with-debian-9.4 Processor:

Python: Implementation: CPython Executable: /usr/bin/python Version: 2.7.13 Compiler: GCC 6.3.0 20170516 Bits: 64bit Build: Nov 24 2017 17:33:09 (#default) Unicode: UCS4

PyVISA Version: 1.9.0

Backends: ni: Version: 1.9.0 (bundled with PyVISA) Binary library: Not found py: Version: 0.3.dev0 ASRL INSTR: Available via PySerial (3.4) TCPIP INSTR: Available USB RAW: Available via PyUSB (1.0.2). Backend: libusb1 USB INSTR: Available via PyUSB (1.0.2). Backend: libusb1 GPIB INSTR: Please install linux-gpib to use this resource type. No module named gpib TCPIP SOCKET: Available

If you have any idea of to control serial instrument with pyvisa-py as using pyserial...

cla

[MatthieuDartiailh]

Pyvisa does not close the connection to your robot after you write to it, which from your pyserial example is required for your robot to move. Try calling the my_inst.close method. Pyvisa assumes that the instrument expect a particular character (write_temination) to consider a command complete and execute it, which the most common case for VISA instrument, which is why it does not close the connection.

[clavay]

The robot moves before the close. It is not necessary, I put it only to close the connection before to try it with pyvisa.

[clavay]

It's ok with this code :

import visa rm = visa.ResourceManager('@py') list = rm.list_resources() my_inst = rm.open_resource(list[0], baud_rate=9600, data_bits=8, parity=visa.constants.Parity.none, stop_bits=visa.constants.StopBits.one, write_termination='') my_inst.write('B+100')

Thank you for your help.

[MatthieuDartiailh]

I am happy you found a solution !