Simulink Instrument Control Toolbox Serial Send Usage

I have a device connected to a serial port of a PC that has Matlab and Simulink installed on it. I would like to communicate with the device via Simulink. I see that there is the Serial Send block in the Instrument Control Toolbox but I have not been successful at sending a simple string of characters to my device. I would like to send the following 7 characters followed by a carriage return character ('\r') every 1 second:

P0 0.75

I am assuming that this is relatively simple to do; can anyone offer some help?

Thank you.