Octagon 5266, Справочное руководство

Страница: 48 / 122

Function and use of serial ports
COM1 as serial console device
You can use COM1 as a console device to communicate with another PC. COM1 is
used as the console device if the Console Redirection in the Features Configuration
menu is set to Redirect. COM1 will also be configured as a console device if a host
computer is connected to COM1 and the host keyboard sends a carriage return
(Enter) during the boot process. If Console Redirection is set to Auto, the V switch
(switch 500 position 2) must be set to Off to redirect video to a serial console. See
the Console devices chapter for more information.
Note When interfacing the 5266 to your desktop PC, you must use a null modem
adapter.
COM1 and COM2 as RS–232 I/O
COM1 is a dedicated 8-wire RS–232 interface. COM2 can be configured through
Setup as an 8-wire RS–232 interface. You can connect up to two RS–232 serial I/O
devices. Note that Switch 2, positions 3 and 4 must remain Off for RS–232 on
COM2.
COM2 as RS–422 or RS–485 networks
COM2 can also be configured in Setup as RS–422 or RS–485. RS–422 and RS–485
use differential signaling to communicate between the devices on a network.
Differential signal reduces the effect of environmental noise, allowing
communication over distances up to 1200 meters.
The RS–422 and RS–485 receivers provide an active high (space) condition for
shorted, open, or inactive lines. Note that RTS is used differently by RS–422 and
RS–485. Review the information in the following sections regarding RTS.
RS–422 is a point-to-point configuration. RS–485 is a multi-node configuration that
allows up to 32 nodes on a network. Refer to table 4–3 on page 47 for switch
settings for terminating an RS–422/485 network.
48