msheed it is hard to understand the problem without even knowing what the error message is.
COM port is the connection point on computer where you connect your pole display. There might be more than one ports so they named as COM1, COM2, etc.. So you should know which port it connected and it properly configured. If it is configured correctly you should be able to send messages to pole display from command prompt. For example typing echo helloo! > COM2 will display helloo! message on pole display that connected to COM2 port. If you can do it SambaPOS commands will work.