Communication
8.6 RS485
S7-200 SMART
446
System Manual, V2.3, 07/2017, A5E03822230-AF
LAD/FBD
Description
STL
Network 3:
Transfer Master out-
puts to CPU outputs.
Copy CPU inputs to
the Master inputs. If in
data exchange mode:
1.
Copy Master out-
puts to CPU out-
puts.
2.
Copy CPU inputs
to Master inputs.
LDB= SMB224, 2
BMB *VD1000, QB0,
VB1008
BMB IB0, *VD1004,
VB1009
8.5.1.14
Reference to the EM DP01 PROFIBUS DP module technical specifications
For further information on the EM DP01 PROFIBUS DP module, refer to the
"EM DP01 PROFIBUS DP module" (Page 775) technical specifications.
8.6
RS485
An RS485 network is a differential (multi-point) network and can have up to 126 addressable
nodes per network and up to 32 devices per segment. Repeaters are used to segment the
network. Repeaters are not addressable nodes; therefore, they are not included in the count
of addressable nodes, but are counted in the devices per segment.
RS485 allows for data transfer at a high speed (from 100 m at 12 Mbit/s to 1 km at 187.5
Kbit/s).
RS485 can operate with the PPI protocol and Freeport:
●
PPI protocol: Can operate on RS485 or RS232 (half-duplex). Possible connections
include:
–
PPI protocol devices
–
RS485 HMI displays
●
Freeport: Can operate on RS485 or RS232 (half-duplex). Possible connections include:
–
RS485-compatible devices (for example, a bar code scanner)
–
Devices that have RS485 interfaces (for example, a control system)
–
Third-party devices using Freeport
–
Modems