In a flex ring with several participants, the data volume per participant is distributed dynamically and calculated by ibaPDA. The data size is calculated by ibaPDA and it depends on the configured number of analog and digital signals and the smallest configured time base in the ring.

Beginning with version 6.33.1, ibaPDA provides a simulator which calculates the data size that can be transmitted via fiber optics with 32Mbit Flex protocol. The simulator is available in the Configuration tab.

The data sizes in bytes of each device on the link and the timebase of the data acquisition on the link (in µs) is needed for the calculation.

The values can be manually entered or taken automatically from the current configura-tion, either with a click on the button <Estimate values from current configuration> or when the respective link of the ibaFOB card is marked in the module tree.

The devices in the Flex ring and the corresponding data sizes are listed in the grid on the left. Address 0 is reserved for the Ethernet channel and is not editable.

The section Flex frame utilization indicates how much of the bandwidth is still available. The color of the section changes with the utilization rate:

  • Green: OK

  • Orange: bandwidth for the Ethernet channel < 3 kB/s

  • Red: too much data configured.

The values taken automatically are initially estimated. After the configuration has been applied with a click on <OK> or <Apply>, the actual data values are displayed on the Info tab.

If too much data is configured, you can either reduce the number of signals to be measured or increase the timebase.

Simulation of the load

Even if no devices have been connected and configured, the calculation of the telegram size can be used for calculating the expected data load in advance.

Open the I/O Manager in ibaPDA, click on the link of the card and select the "Configuration" tab.

Set the smallest planned sampling time in the Timebase field. Now, you can enter manually the planned or expected data amount (in bytes) in the table rows 1 to 15. With every new entry, the result values in the Flex frame utilization field are recalculated.

This allows you to estimate whether the planned number of signals or devices can be processed on one Flex link or whether an additional Flex link should be used.
Reserved bandwidth in the Ethernet channel for configuration data

The Ethernet channel (address 0) is used to transmit configuration data, to communicate with the web interface and especially with ibaBM-DP for the display of the PROFIBUS diagnosis. If many devices are configured with a lot of signals, it may happen that only the minimum size of 1 kB/s is reserved for the Ethernet channel. This is not sufficient in many cases and may cause, that the PROFIBUS diagnosis cannot be displayed or the communication with the web interface is very slow.

It is now possible to reserve a fixed bandwidth for the Ethernet channel with the option Reserve bandwidth for ethernet communication. The default value of 4 kB/s is usually sufficient for configuration data and Profibus diagnosis.