Texas Instruments S251B Manuale Utente
21
April ’00
Chapter 2. Hardware
Figure 5: RS422/RS485/DAT Switches
Figure 6: Synchronization DIP Switches
Table 23: RS422/RS485/DAT Settings DIP Switches
Switch
OFF
ON
1
RS422
RS485
2
RS422
RS485
3
-
RS422/RS485 Rx+/Rx-
line-to-line termination (120
Ω
)
4
DAT Disabled
DAT Enabled
5
DAT LEDs Disabled
DAT LEDs Enabled
Notes:
SW1 and SW2 must always be in the same position as each other,
either both OFF or both ON.
either both OFF or both ON.
Table 24: Synchronization DIP Switches
Switch
OFF
ON
1
-
Synchronization Rx+ line pull-up (180
Ω
)
2
-
Synchronization Rx- line pull-down (180
Ω
)
3
-
RS422/RS485 Rx+/Rx- line-to-line
termination (120
Ω
)
4
Set the RFM to Master
Set the RFM to Slave in CPS Bus
5
-
CPS line-to-line termination (120
Ω
)
ON
1
ON
1