ibaBM-DP
Manual
Issue 1.7
147
Fig 119: ibaLogic, output signal to S7
4.
Start the SIMATIC-Manager, enter a new variable table and display the transmitted
generator signal (DB13.DBW6) in INT format.
13.4.2 Reloading S7 Application Data from/to DP Master
When assigning the slaves in the master system several data blocks are defined in the
peripheral address space at the same time. The block-wise reloading of data is used to
reach a higher security and a better detection of short termed failures.
In order to reload the data from or to the periphery the use of SFC14 and SFC15 is
recommended.
When dealing with the S7-300 family more than one call of SFC14/SFC15 is required
because the data block length is limited to 32 Bytes. When working with the S7-400
family, 122 Bytes are available per data block. This is the reason why you find different
GSD files on the DVD.
13.4.3 DP Faults with S7 Master may cause Zeros in Data
Please note that slave data can be overwritten with zeros in case of a DP slave failure.
Such failures can lead to zeros or no values in the data flow, even for a few milliseconds.
In real time automation systems this effect may cause failures of the entire system which
are hard to examine.
Concerning incoming data (master's view), there are some possibilities using the DP
monitoring functions of the S7-system, such as alert function blocks.
When it comes to outgoing data the receiving systems, which are connected to the PRO-
FIBUS via ibaBM-DP and interface boards like ibaLink-VME or ibaLink-SM-64-io, can
only read 32 analog and 32 digital data per slave (= module in ibaPDA) from the iba
interface cards.
On that end even the breakdown of the entire DP line cannot be detected. In case of a
PROFIBUS failure the most recent signal values remain.
