COM1 as serial console device
You can use COM1 as a console device to communicate with another PC. For COM1
to be a serial console, the “V” video jumper W1[5–6] must be removed. See the
Console devices chapter for more information.
Note
When interfacing the 2060 CPU Card to your desktop PC, you must use a null
modem adapter.
COM ports as RS–232 I/O
COM1 and COM2 are 8-wire RS–232 interfaces. You can connect two serial I/O
devices. COM1 is always configured as RS–232. COM2 must be enabled in BIOS
Setup.
In the default configuration, the video jumper W1[5–6] is installed. This jumper
automatically disables the Serial Video option in the Advance menu in Setup, and
the COM1 port is available for serial I/O devices. In some instances, such as
running a program on the 2060 CPU Card that will ultimately be used on another
card without on-board video, you might want to remove the video jumper and still
use COM1 as a COM port instead of a serial console. In this instance, you must go
into Setup and set Serial Video in the Advanced menu to Disabled.
COM2 as RS–422 and RS–485 networks
COM2 can be used 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 a marking 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. COM2 can be configured in BIOS Setup as
either RS–232, RS–422, or RS–485. Refer to table 5–4 on page 51 for jumper
settings for terminating an RS–422/485 network.
RS–422
RS–422 is typically a point to point configuration. RS–422 is also specified for
multi-drop (party-line) applications where only one driver is connected to, and
transmits on, a “bus” of up to 10 receivers. The device at the end of an RS–422
network must be terminated. The 2060 CPU Card optionally terminates with a
100 ohm resistor. Refer to Table 5–4. Figure 5–3 shows a typical RS–422 four-wire
interface circuit.
The RTS signal must not be enabled by the software or the RS–422 transmitter will
be disabled.
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