Vaisala PTU200 - Manual (Page 26)

U SER ' S G UIDE _______________________________________________________________________
22 ___________________________________________________________________ M210195 EN -A
With the connector X15 the user can select the RS 232C (RX, TX) or
TTL levels for serial communication. With TTL levels, the user also
has phase alternatives available for both input (RXD, RXD inverted)
and output (TXD, TXD inverted).
TXD
RXD
X15
RX/RXD
TX
TXD
F IGURE 4-2 RS 232C/TTL level and phase selections
The half duplex two-wire RS485/422 serial interface of the PTU200
does not require any hardware settings to be made to the transmitter.
See page 53 for quick reference information on how to use the
RS485/422 interface of the PTU200 series digital transmitters.
Normally, the dip switch S1 settings are all OFF as in F IGURE 4-3
ON
OFF
SW1
SW2
SW3
SW4
SW5
SW6
SW7
SW8
S1
F IGURE 4-3 Basic dip switch S1 settings
An external power control can be used to switch the PTU200
transmitter
ON/OFF. The control is activated with the switch SW2 in
position ON as shown in F IGURE 4-4 . The TTL signals are: 0VDC OFF
and 5VDC ON.
ON
OFF
SW1
SW2
SW3
SW4
SW5
SW6
SW7
SW8
S1
F IGURE 4-4 External power control ON