Communication
6.6 Communication via USS
Control Units CU240S
Operating Instructions, 07/2008 - FW 3.2, A5E00766042B AD
175
6.6
Communication via USS
6.6.1
Universal serial interface (USS)
Data
Parameter range:
P2010 … r2037
Warnings:
–
Faults:
F0071, F0072
Function chart number:
FP2500, FP2510, FP2600, FP2610
Description
Using the Universal Serial Interface (USS) protocol, a user can establish a serial point-to-
point data link (RS232 interface) and a serial bus data link between a higher-level master
system and several slave systems (RS485 interface). Master systems can be e.g. PLCs (e.g.
SIMATIC S7-200) or PCs. The inverters are always the slaves on the bus system.
The USS protocol allows the user to implement both automation tasks with cyclical telegram
traffic (a fixed telegram length is necessary) as well as visualization tasks. In this case, the
protocol with variable telegram length is advantageous, as texts and parameter descriptions
can be transferred in one telegram without chopping up the information.
USS via RS232
With the RS232 interface only direct connections (point-to-point) are possible with cable
lengths of 2 m … 5 m typically. This is typically used to commission a drive where the
commissioning software (e.g. STARTER) runs on a PC. For this configuration the optional
PC Connection Kit is available.
USS via RS485
With the RS485 interface communication
networks can be constructed. The topology
must be that of a line with the first and last
devices of the line terminated with
termination resistors. The figure shows the
termination DIP switch on the CU240S.
Default position is OFF (no termination
resistor).
2
)
)2
1
Short branches are possible to connect the devices. Up to 31 inverters can be integrated as
slaves into a network with a PLC as master.
