How do you configure a PROFIBUS PA network in STEP 7?
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.
Configuration of the connection of the PA slaves (Fig. 1) in STEP 7 HW Config is explained in the following hardware configuration.
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.
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.
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.
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.