Advantech AIMB-706, User Manual

Page: 21 / 106

11 AIMB-706 User Manual
C
ha
pte
r 1
H
ard
w
are
C
on
fig
ura
tio
n
1.8.6 COM3 RS-232/422/485 jumper setting (JSETCOM3)
Use JSETCOM3 to select the RS-232/422/485 mode for COM3. The default setting
is RS-232. While RS-485 is selected, change device mode to RS-485 if further
choice of auto flow control under BIOS menu is necessary. Please refer to Chapter
3.2.2.10.
1.8.7 COM3 RS-422/485 termination resistor (JT1, JR1)
To stabilize communications, JT1 and JR1 use enable or disable 120 ohm of termina-
tion resistor at board side for COM3 RS-422/485 mode to match impedance, depend-
ing on user’s device application. JT1 is for TX signal line; JR1 is for RX signal line.
Table 1.7: COM3 RS-232/422/485 jumper setting (JSETCOM3)
Function Jumper Setting
*RS-232
RS-422
RS-485
* default setting
Table 1.8: COM3 RS-422/485 termination resistor (JT1, JR1)
Function Jumper Setting
Disable termination
*Enable termination
* default setting
1-2 closed
1 2 3
2-3 closed
1 2 3