Our sample ladder logic with give you information received in on the serial port into an array like ReadString. This information is populated once the termination condition has been met. This termination condition tells our module when to assume that you are done receiving information on the serial port and it is OK to send that string to the processor. As for transmitting data out the port, simply populate the WriteString location with the data that you wish to send, and place the number of characters that you wish to send out the port in the WriteLength field. The module will see this WriteLength being greater than 0, and send that information in the WriteString array out to the slave device.