Vaisala PTB220 User Manual
Page 45
C
HAPTER
5_______________________________________________________________
INSTALLATION
V
AISALA
_________________________________________________________________________ 39
T
ABLE
5-2
Pin assignment for RS 232C/485/422
PIN
SIGNAL
1
TX with diode
2
TX/TXD/TXD inverted
3
RX/RXD/RXD inverted
4
external power on/off control
5
ground for the RS 232C
6
RS 485/422 LO
7
ground for supply voltage and TTL level serial
interface
8
RS 485/422 HI
9
supply voltage (10...30 VDC)
In barometers with RS232/analog output, the pin assignment is as
follows.
PIN
SIGNAL
1
TX with diode
2
TX/TXD/TXD inverted
3
RX/RXD/RXD inverted
4
external power on/off control
5
ground for the RS 232C
6
voltage output (0...5 VDC) / current output (4...20 mA)
7
ground for supply voltage
8
voltage output ground / current output ground
9
supply voltage (10...30 VDC)
It is possible to connect multiple PTB220 series barometers to one RS
232C interface by using the terminal ´TX with diode´ of the barometer
(see
F
IGURE
5-3
). This feature is useful when several PTB220 series
barometers must be fine adjusted and calibrated in one batch. See
Appendix F for quick reference information on how to use one
RS232C interface for multiple PTB220 series barometers.
GND
GND
TX WITH DIODE
RX
GND
RX
GND
RX
TX
HOST
COMPUTER
TX WITH DIODE
TX WITH DIODE
PTB220 # 1
PTB220 # 2
PTB220 # 3
RX
F
IGURE
5-3
Multiple PTB220 barometers on one RS 232C interface