Siemens SIMATIC HMI OP 77B Operating Instructions Manual page 22

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Configuring the interface
The RS 422/RS 485 interface can be configured by
changing the switch settings on the DIL switch. In this
case, the RS 422 receive data and RTS signal are
interchanged.
Normally, the RTS signal is not required by the PLC.
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1 Rear panel cover
2 DIL switch
3 Illustration of the switch setting
Figure 4–3 Position of the DIL switch
Note
Pay attention to the DIL switch settings on the rear of
the HMI device depicted in the diagrams – also refer to
Table 4-1.
The following table describes the DIL switch settings
according to the communication to be selected. The
switch settings relate to Figure 4–3.
4–4
Release 03/2004
Operating Instructions (Compact) OP 77B
6AV6691-1EA01-0AB0
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