VTAP50 OEM MODULE INSTALLATION GUIDE
PAGE 7
The connector J1 includes both USB and RS232 signals, as follows:
Pin
Function
1
GND
2
USB D+
3
+5V supply
4
USB D-
5
RS232 RXD (input)
6
Reserved (sense input)
7
RS232 TXD (output)
8
Reserved (sense GND)
Figure 3-5 Typical RS232 cable
A typical RS232 cable has the following DB9 female connector pinout:
Pin
Function
2
TXD
3
RXD
5
GND
9
+5V supply
A PC or terminal RS232 connector is usually DTE (data terminating equipment), typically a
male DB9 with TXD on pin 3 and RXD on pin 2. The appropriate connecting cable is then a
DCE (data communications equipment) female DB9. TXD and RXD pins are swapped
between the DCE and DTE devices, so that the transmit pin on one connects to the receive
pin on the other.
The VTAP50 requires a 5V power supply, but not all RS232 devices have 5V on pin 9.
Either:
l
Disconnect the USB cable before making the serial connection, if power will be provided
by J1 (pins 1 and 3) and the serial cable/host.
l
Or retain a USB connection in addition to the serial connection, if power is not available
from your RS232 device.
Some serial cables have a separate DC 5.5/2.1mm barrel connector to supply power. In
these cables, typically, the centre pin is +5V and the outer barrel is GND.
