Installation and Configuration
Communications
22 Operating Manual for RS-232 for XT/HPD Series Power Supply
Flow Control
Selection
Flow control signals regulate data flow for proper communication. Use the
FLOW switch on the rear panel S1 switch to select flow control or to disable
flow control. With flow control enabled, you can use either software or hardware
protocols to control flow rates. Table 2.3 gives the FLOW switch settings with
regards to the markings on the subplate rear panel. For a diagram of the rear
panel subplate, see Figure 2.2, on page 16.
Table 2.3 Flow Control Section
Once you select the flow control option, you have to select either software flow
control or hardware flow control using the CTS/XO switch (SW1-4) on the rear
panel of the power supply. Software flow control uses XON/XOFF protocol
while with hardware flow control you have the choice of RTS/CTS or DTR/DSR
protocol. Table 2.4 shows the flow control conditions in reference to the
CTS/XO switch. To change the hardware flow control protocol, refer to Table
2.3 in this section. Figure 2.2, “Power Supply Rear Panel with RS-232 Interface
Installed” on page 16 shows the location of the SW1 switch on the power supply
rear panel.
Table 2.4 Hardware/Software Flow Control Selection
Software
Flow Control
This software protocol uses special characters that synchronize device
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.
FLOW Switch Setting Condition
0Disable Flow Control
1Enable Flow Control
XON Switch Setting Condition
0Hardware Flow Control
1Software Flow Control