20-3
PPC Manual Revision 1
Chapter 20: Modbus Communication
Overview of Modbus Communication Connection
RS-485
SCADA software
(commercially available)
RS-485
converter
Up to 31 connected slaves with a maximum length of 1200 m
Model USB-485M is recommended
(purchased separately)
Comparison of RTU and ASCII Modes
Item ASCII Mode RTU Mode
“
”.
“
”
Detection of Message Frame Termination in RTU Mode
Frame 1 Frame 2
Time
3.5 chars or more 3.5 chars or more
Note
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