Vaisala PTB330 - Manual (Page 45)

Chapter 3 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 43
Installation and Wiring
1. Disconnect the power. If the RS-485-module is installed in the
factory, continue with the item 4.
2. To attach the module, open the barometer cover and fasten the
RS-485 module to the bottom of the housing with four screws
on the module slot 1.
3. Connect the flat cable between the RS-485 module and the
motherboard's pins MODULE1 (Communications).
4. Pull the network wirings through the cable gland.
5. Connect the twisted pair wires (1 or 2 pairs) to the screw
terminals as presented in Table 5 on page 44.
6. Connect the RS-422/RS-485 common wire/shield to screw
terminal COMMON.
7. If you use RS-485 (or RS-422) to connect just one barometer to
a master computer, enable the internal termination of the
barometer by switching switches 1 and 2 ON. Make sure that the
master's end of the line is also terminated (by using master's
internal termination or with a separate terminator).
8. If you are connecting several barometers to the same RS-485
bus, make sure that switches 1 and 2 are OFF and terminate the
bus with separate terminators at both ends. This allows
removing any barometer without blocking the bus operation.
9. Use the bus type (4-wire/2-wire) to select the selection switch 3.
10. In 4-wire mode RS-485 master sends data to the PTB330
barometer through terminals RxD1+ and RxD0- and receives
data from PTB330 barometer through terminals TxD1+ and
TxD0-.
11. When operating in communication mode RS-422, set both
switches 3 and 4 to ON position (4-wire wiring is required for
RS-422 mode).
12. Connect the power and close the cover.
13. If you are replacing an existing module, the installation is
complete. If you are adding a new module, continue to the next
step.
14. Connect to the service port, and execute the MODS command to
register the changes.
15. Switch the power off and back on again to clear related errors
and to activate the changes.