Endress+Hauser Proline Promag P 100 - Page 31

Proline Promag P 100 Electrical connection
Endress+Hauser 31
• If the device is operated with a baud rate of 1.5 MBaud and under:
For the last transmitter on the bus, terminate via DIP switch 2 (bus termination) and DIP
switch 1 and 3 (Bus polarisation). Setting: ON – ON – ON
(→  14,  31).
• For baud rates > 1.5 MBaud:
Due to the capacitance load of the user and the line reflections generated as a result, ensure
that an external bus terminator is used.
It is generally advisable to use an external bus terminator as the entire segment can fail
if a device that is terminated internally is defective.
390 Ω
DIP 1
5V
26
27
220
Ω
DIP 2
0V
390 Ω
DIP 3
OFF
ON
1
2
3
4
Bus polarisation
Bus termination
Bus polarisation
Not used
4.
1.
2.
3.
A0021274

14 Termination using DIP switches on the I/O electronics module (for baud rates < 1.5 MBaud)
Modbus RS485
To avoid incorrect communication transmission caused by impedance mismatch, terminate
the Modbus RS485 cable correctly at the start and end of the bus segment.