Siemens Welding System ST PCS 7 User Manual
Communication
PROFIBUS PA
Routers: DP/PA link and DP/PA coupler
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Siemens ST PCS 7 · November 2007
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Overview
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
The following criteria can be applied when choosing the network
transition:
• DP/PA coupler:
• 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
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Application
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)
• 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
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
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-
nostics slave).
PROFIBUS diagnostics with FDC 157-0 DP/PA coupler,
configured as PROFIBUS diagnostics slave
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
• 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
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 AG 2007