Table 2-5 X-Com-2 Mode Settings (Switch 3); Table 2-6 X-Com-2 Termination Settings (Switch 2) - Octagon Systems X-COM-2 Reference Manual

Switch settings for mode (RS–422 or RS–485)
COMA and COMB can be used for RS–232, RS–422 or RS–485. RS–232 is
always available at connectors J3 and J4. Connectors J1 and J2 can be
individually programmed as RS–422 or RS–485. Note that you cannot use the
same port simultaneously for RS–232 and RS–422/485.
Positions 7 and 8 on Switch 3 select the mode for the corresponding port.
Position 7 is for COMB, and position 8 is for COMA. Table 2–5 shows the
switch settings for selecting the mode. Setting a switch to On selects RS–422
mode. Setting a switch to Off selects RS–485 mode. By default the X–COM–2
card is set for RS–422 mode on both ports (both switches On).
Table 2–5 X–COM–2 mode settings (Switch 3)
Switch
position #
7
7
8
8
* = default
Switch settings for termination (RS–422 and RS–485 mode)
If COMA or COMB is used for RS–422 or RS–485, and the port is at the end
of the network, the port must be terminated. Switch 2 terminates the
network. If the COM port is not at the end of the network the switches must
be set to unterminated.
Positions 1 and 2 on Switch 2 select the termination mode for COMA. Setting
these switches to On terminates COMA. Positions 3 and 4 on Switch 2 select
the termination mode for COMB. Setting these switches to On terminates
COMB. Setting the switches to Off makes the corresponding port
unterminated. Table 2–6 shows the switch settings for selecting the
termination mode. By default the X–COM–2 card is set for both ports
terminated (all switches On).
Table 2–6 X–COM–2 termination settings (Switch 2)
Port
COMA
COMA
COMB
COMB
* = default
Switch Setting
Off
On*
Off
On*
Switch Switch
position # Setting
1 On*
2 On*
3 On*
4 On*
12
Mode Port
RS–485 COMB
RS–422 COMB
RS–485 COMA
RS–422 COMA
Mode Switch
Setting
TX terminated Off
RX terminated Off
TX terminated Off
RX terminated Off
Mode
TX unterminated
RX unterminated
TX unterminated
RX unterminated