Siemens ASM 456 Operating Instructions Manual page 29

Connecting up the terminating resistor for PROFIBUS DP
A PROFIBUS DP segment must be terminated at both its ends, in other words, on the first
and last node of the segment, with its characteristic impedance.
If the ASM 456 is the last PROFIBUS node, then you must terminate PROFIBUS DP with
the M12 terminating resistor. For the order number, refer to the section "Ordering data".
1. Plug the M12 terminating resistor into the right-hand M12 circular socket connector Loop-
through on the terminal block. Make sure the interlock has properly engaged.
2. Use the knurled locking ring to secure the M12 terminating resistor.
Figure 4-8
Closing unused sockets
Always close all unused sockets using M12 or 7/8" sealing caps in order to achieve the
degree of protection IP65, IP66 or IP67. For order numbers, refer to the section "Ordering
data".
ASM 456 interface module
Operating Instructions, 07/2015, J31069-D0162-U001-A6-7618
Connecting the M12 terminating resistor
4.3 Wiring connection block M12, 7/8"
Connection
29