I'm try to get force and torque from FT300, but failed. I download the visual demo from https://robotiq.com/support, but it didn't work, no data curve. I tried the python script from https://dof.robotiq.com/discussion/2379/read-ft300s-data-stream-at-100hz-with-python, but only get an error:
minimalmodbus.InvalidResponseError: Checksum error in rtu mode: 'J\x0b' instead of 'ZÝ' . The response is: '\x8eÿ\n\t \x98Jbè\x0eÿJ\t@\x0eJ\x0b' (plain response: '\x8eÿ\n\t \x98Jbè\x0eÿJ\t@\x0eJ\x0b').
How can I get the true data from FT300? Any help much appreciated.

First step is to try using the pc software provided on our support webpage to visualize forces. If it does not work you may not have to do e the connection properly. Please contact support@robotiq.com if you cannot manage to use the pc software. 

Thanks. Problem solved. I cut off the power supply, reboot FT300 and get the force correctly.