Siemens ST PCS 7 manual Routers DP/PA link and DP/PA coupler, Overview Application

© Siemens AG 2007

Communication

PROFIBUS PA

Routers: DP/PA link and DP/PA coupler

■Overview ■Application

To create a smooth network transition between PROFIBUS DP and PROFIBUS PA, the SIMATIC product range offers two ver- sions: the DP/PA coupler and the DP/PA link.

The following criteria can be applied when choosing the network transition:

•DP/PA coupler:

For small quantity frameworks (volumes of data) and low tim- ing requirements; limiting of data transfer rate on the PROFIBUS DP to 45.45 kbit/s

•DP/PA link:

For large number of stations and high cycle time require- ments; data transfer rate on the PROFIBUS DP up to 12 Mbit/s

The two DP/PA routers are based on two versions of the

DP/PA coupler:

•Ex [i] DP/PA coupler (max. output current 110 mA)

for implementation of PROFIBUS PA networks with a line or tree topology in environments up to Ex zone 1, not for redun- dant architectures (coupler redundancy, ring)

•FDC 157-0 DP/PA coupler (max. output current 1000 mA)

for implementation of PROFIBUS PA networks with a line, tree or ring topology in environments up to Ex zone 2; can be used for the redundant architectures "Ring" and "Coupler redun- dancy"

DP/PA couplers are also integral components of the DP/PA link (see design). The DP/PA link connects PROFIBUS DP and PROFIBUS PA together, and decouples the transmission rates. In contrast to the DP/PA coupler which limits the data transmis- sion rate on the PROFIBUS DP to 45.45 kbit/s, the DP/PA link does not influence the performance of the PROFIBUS DP.

The DP/PA link functions as a slave on the PROFIBUS DP and as a master on the PROFIBUS PA. From the viewpoint of the host PROFIBUS DP master, the DP/PA link is a modular slave whose modules are the devices connected on the PROFIBUS PA. Ad- dressing of these devices is carried out indirectly via the DP/PA link which itself only requires one node address. The host PROFIBUS master can scan devices connected to the DP/PA link all at once.

If the router is a DP/PA coupler, the nodes on the PROFIBUS PA are directly addressed by the PROFIBUS DP master (controller). The DP/PA coupler is an electrical node, but is transparent for communication between the master and PA field devices; it therefore does not require setting of parameters or addresses (exception: FDC 157-0 DP/PA coupler used as PROFIBUS diag- 9 nostics slave).

PROFIBUS diagnostics with FDC 157-0 DP/PA coupler, configured as PROFIBUS diagnostics slave

FDC 157-0 DP/PA couplers configured as PROFIBUS diagnos- tics slaves supply extensive diagnostic and status information via PROFIBUS for swift location and clearance of faults:

•I&M data (Identification & Maintenance)

•Current and voltage values on the main cable

•Redundancy status

•Wire breakage

•Short-circuit

•Signal level

For this purpose, each FDC 157-0 DP/PA coupler requires its own PROFIBUS address. This applies independent of use in a DP/PA link or as a DP/PA router.

The DP/PA link and DP/PA couplers as DP/PA routers can be mounted on an S7-300 profile rail. They are operated with 24 V DC, and can be installed in environments up to Ex zone 2 with extended temperature range.

Siemens ST PCS 7 · November 2007

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