Endress+Hauser Proline Promass 83 - Configuring the Terminating Resistors

Proline Promass 83 PROFIBUS DP/PA Operation
Endress+Hauser 53
5.6.3 Configuring the terminating resistors
!
Note!
It is important to terminate the RS485 line correctly at the start and end of the bus segment since
impedance mismatch results in reflections on the line which can cause faulty communication
transmission.
#
Warning!
Risk of electric shock. Exposed components carry dangerous voltages.
Make sure that the power supply is switched off before you remove the cover of the electronics
compartment.
• For baudrates up to 1.5 MBaud, the termination is set via the terminating switch SW 1 for the
last transmitter on the bus: ON – ON – ON – ON.
• Device is operated with a baudrate >1.5 MBaud: due to the capacitive load of the user and the
resulting line reflection, make sure that external termination is used.
In addition, the signal lines have to be protected for flexible assignment boards (order versions
83***-***********V and 83***-***********P) → Ready screened lines.
The miniature switch for termination is located on the I/O board (see Figure):
F06-x3MBxxxx-16-xx-06-xx-003
Fig. 31: Configuring the terminating resistors (for baudrates < 1.5 MBaud)
A = Factory setting
B = Setting at the last transmitter
!
Note!
It is generally recommended to use external termination since if a device that is terminated
internally is defect, then it can result in the failure of the entire segment.
1
2
3
4
W
E
N
O
1
2
3
4
W
E
N
O
1
2
3
4
W
E
N
O
I
N
P
U
T
/
O
U
T
P
U
T
4
I
N
P
U
T
/
O
U
T
P
U
T
3
1
2
3
4
W
E
N
O
1
2
3
4
W
E
N
O
1
2
3
4
W
E
N
O
1
2
3
4
W
E
N
O
1
2
3
4
W
E
N
O
390 W
+5V
A
3
4
1
2
OFF ON
220 W
390 W
SW 1
390 W
+5V
B
3
4
1
2
OFF ON
220 W
390 W
SW 1