Connecting To The Rs485 Bus (Pac3120 Only) - Siemens SENTRON PAC3120 Manual

4.4

Connecting to the RS485 bus (PAC3120 only)

Procedure
Connect the PAC3120 to the RS485 bus via the integral interface. Please pay attention here
to the general topology of the two-wire line.
1. Connect all three lines to the screw terminals.
2. Ensure a bus terminating resistance is set at the first and last communication node.
Block diagram
TER Bus termination resistor (termination)
PU Pull-up resistor
PD Pull-down resistor
①
Grounding of the cable shield
②
Grounding of the common line, preferably only at one point for the whole bus
Figure 4-15 Block diagram: General RS485 topology
PAC3120 and PAC3220
Equipment Manual, 10/2019, L1V30425208F-01
4.4 Connecting to the RS485 bus (PAC3120 only)
Connection
53