3-52 BOP HIPWR 1113153.5.6 RS232-C OPERATIONThe BOP may be operated via an RS232-C terminal, or from a PC using a terminal emulationprogram. The default settings are as follows:• Baud rate: OFF• Parity: None• Data Bits 8• Stop Bits 1• Prompt DISABLE• XON/XOFF ENABLETo change baud rate, or select prompt, echo or XON/XOFF, refer to PAR. 3.5.3.2 and Table 3-16.3.5.6.1 SERIAL INTERFACEThe serial interface behaves like the GPIB interface in that the command is parsed after receiv-ing a control character of either a Line Feed or Carriage Return. The serial interface supports sixspecial control characters. The six special control characters are:Escape (1BH) Causes the input buffer to be cleared. This character is used to ensurethat the buffer is empty when the host powers on since it is possiblethat the BOP was previously powered on and received some charac-ters prior to the initialization of the host computer.Backspace (08 H ) Causes the last character in the input buffer to be removed from theinput buffer queue.Carriage Return (0D H ) Causes the input buffer to be parsed by the BOP.Line Feed (0A H) Causes the input buffer to be parsed by the BOP.3.5.6.2 RS 232 IMPLEMENTATIONThe following paragraphs are provided to help the user understand how the RS 232 serial inter-face is implemented in the BOP. Since the RS 232 protocol does not use a parity bit, TheXON/XOFF method of communication is selected as the default to ensure “handshake” controlof serial communication.The echo mode is an optional method used to ensure reliable communication between the com-mand originator (computer) and the BOP power supply, thus avoiding a more complex “hand-shake” protocol. When the BOP is in the RS 232 echo mode it returns all data sent to the hostcontroller.The BOP provides an additional option that allow handshake communication: the Promptmethod. By using the handshake options (prompt and XON XOFF) the host controller canensure that serial data interrupts occurring after parsing of the incoming message do not resultin lost data.Figure 3-17 illustrates the echo mode, the prompt method and the default XON XOFF methoddescribed in the following paragraphs.
