Xantrex Technology RS232-XPD manual XON Switch Setting Condition

Installation and Configuration

Communications

Once flow control is selected as option, two flow control methods are available. You can use the rear panel XON switch to select either software-based XON/XOFF flow protocol or hardware-based CTS/RTS or DTR/DSR flow protocol. Table 2.4 shows the flow control conditions with regards to the markings on the rear panel subplate. For a diagram of the rear panel subplate, see Figure 2.2, on page 17.

Table 2.4 Hardware/Software Flow Control Selection

XON Switch Setting	Condition
1	Hardware Flow Control
	(CTS/RTS or DTR/DSR protocol)
0	Software Flow Control
	(XON/XOFF protocol)

Software This software protocol uses special characters that synchronize device

Flow Control communications. The device sends the control code XOFF (ASCII value 13 hex) when it is not ready to receive data. The device sends the control code XON (ASCII value 11) when it is ready to resume receiving data.

To choose XON/XOFF protocol, select the XON switch position shown in

Table 2.4.

Hardware Hardware flow control protocol requires a dedicated control line on the RS-232 Flow Control cable. The dedicated control line is needed so that the device can signal the controller

when it is ready to receive data. You can designate either RTS/CTS or DTR/DSR protocol for the RS-232 interface.

Set the XON switch for hardware control using the information in Table 2.4. With hardware flow control selected, RS-232 Interface PCB jumpers J16 and J17 dictate the type of flow protocol. Table 2.5, “Jumper/Pin Settings for RTS/CTS Flow Control (Default)” and Table 2.6, “Jumper/Pin Settings for DTR/DSR Flow Control (Default)” identify jumper connections and input and output pin designations for each protocol. See also “Transmit / Receive Pin Selection” on page 22 for RS-232 connector pinouts.

Note:When resetting the flow control switches during a working session, turn the power supply OFF and then ON again to ensure that the new settings are put into effect.

Table 2.5 Jumper/Pin Settings for RTS/CTS Flow Control (Default)

	Jumper Connections	RS-232 Connector Pin
RTS (Input to RS-232)	J17 to 2-4 and 3-5	7
CTS (Output to RS-232)	J16 to 1-3 and 4-6	8

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