© National Instruments
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1-25
RS-232 Serial Port
The cDAQ controller has an RS-232 serial port, shown in Figure 1-1, to which you can connect
devices such as displays or input devices. Use the Serial VIs to read from and write to the serial
port. Refer to the
LabVIEW Help
for information about the Serial VIs. Refer to Figure 1-19 for
pin locations and signal descriptions.
Figure 1-19.
RS-232 Serial Port Pin Locations
You can use the Ring Indicator (RI/WAKE) on pin 9 to wake the controller from a low power
state. You can drive RI/WAKE with logic-level signals where a high level greater than 2.4 V
signals a wake event.
RS-485/422 Serial Port
The cDAQ controller has an RS-485/422 serial port, COM 2, accessible through a 10-position
RJ-50 modular jack. The shield of the RJ-50 connector is isolated from the controller, enabling
you to use shielded cables while maintaining isolation. The RS-485/422 serial port is shown in
Figure 1-1. Refer to Figure 1-20 for pin locations and signal descriptions.
Figure 1-20.
RS-485/422 Serial Port Pin Locations
COM 2 is designed to operate in four-wire (RS-422) or two-wire mode.
NI offers a DIN rail-mountable screw terminal adapter (NI part number 778674-01) that you can
use to connect termination resistors to COM 2.
5
9
4
8
3
7
2
6
1
DCD
RXD
TXD
DTR
GND
D
S
R
RT
S
CT
S
RI/WAKE
1 No Connect
2 TXD–
3
TXD+
4 No Connect
5 No Connect
6 RXD–
7 RXD+
8
No Connect
9 No Connect
10 I
s
ol
a
ted GND