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Entry type: FAQ Entry ID: 22729270, Entry date: 11/27/2007

How do you configure a PROFIBUS PA network in STEP 7?

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There are several ways of connecting and configuring PA slaves when configuring a PROFIBUS PA network.

PA slaves are always connected directly to the DP/PA coupler. The DP/PA coupler can be connected directly to the PROFIBUS DP or via a DP/PA link. The type of connection affects the configuration and depends on the performance required and the quantity structure of the system (see Entry ID: 21562130).

Connection to the DP/PA coupler without DP/PA link

  • The baud rate of 45.45 kbit/s must be set on the PROFIBUS DP.
  • You do not need a GSD file to configure the DP/PA coupler (the DP/PA coupler works bus transparent).
  • The PA slaves are projected simply as DP slaves.
  • The diagnostics of the PA slaves is according to the mechanisms of PROFIBUS DP, i.e. you can access each separate PA slave with SFC 13 or SFC 51.

Fig. 1
Configuration of the connection of the PA slaves (Fig. 1) in STEP 7 HW Config is explained in the following hardware configuration.

Fig. 2 
Connection to the DP/PA coupler with DP/PA link
  • The IM 157 is configured as DP slave and has a lower-level PROFIBUS PA, on which the IM 157 is PA master.
  • PROFIBUS DP can be operated at a baud rate of up to 12 Mbit/s.
  • Diagnostics of the IM157 is via SFC 13 or SFC 51.
  • Diagnostics of the lower-level PA slaves is via SFC 59 "RD_REC" if the DP/PA link is operated on a DPV0 master and via SFB 52 "RDREC" if the DP/PA link is operated on a DPV1 master.

Fig. 3

When configuring the DP/PA link from the STEP 7 integrated knowledge (STEP 7 hardware catalog folder PROFIBUS DP > DP/PA link > IM 157) the hardware configuration is as follows.

Fig. 4
If the version of the DP/PA link is more recent than the version of your STEP 7, you must configure the DP/PA link via GSD file. The GSD file that can be downloaded from Entry ID: 113602 is configured after installation (see Entry ID: 2383630) from the hardware catalog folder PROFIBUS DP > Other Field Devices > Gateway > PA > DP/PA link (IM157). The hardware configuration here looks like this.

Fig. 5
Notes on configuring the DP/PA link via GSD file

  • A description of how to configure the PA address can be found under Entry ID: 22729489
  • The procedure for configuring PA slaves that are not in the GSD file is described in Entry ID: 26562190
  • You will find information in the "PA System Description" manual in Entry ID: 1174285 or in the manual "DP/PA Link and Y Link Bus Couplings" in Entry ID: 1142696.
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