I'm trying to use a usb-to-rs232 adapter to send a serial command to a device connected to the rs232 port. When I login into screen using `screen /dev/cu.usbserial 9600` and then enter my command from within the screen program, I get the expected response.

What I'm now trying to do is send a single serial command via a command line, but can't get my syntax quite right.

Here's an example of what I'm trying:

```
screen -dmS -p 0 /dev/cu.usbserial 9600 "MVUP"

```

...where MVUP with a carrier return is all I'm needing to send. I don't need to read a response back. Environment is OS X 10.7 and using the default bash shell.