The Flex protocol works with a data transfer rate of 32 Mbit/s and supports up to 15 "Flex-capable" devices connected in a ring topology.

With 32Mbit Flex, the data volume and the sampling rate can be selected in a flexible way. The transferred data volume per cycle depends on the sampling rate. Generally, the following applies: The less data that is transferred, the higher the possible sampling rate.

For the signals to be measured, sampling rates of 500 Hz to 100 kHz can be realized, which correspond to a timebase from 10 µs up to 2 ms. The maximum sampling rate also depends on the acquisition device and can be found in the device manual. In ibaPDA you can select even lower sampling rates down to 1 Hz. This corresponds to a timebase of 1000 ms. In this case, the timebase in the Flex ring is set to 2 ms and subsampling is carried out in ibaPDA. Data which is not relevant for the configured sampling rate is dropped by ibaPDA.

With 32Mbit Flex, up to 4060 bytes per cycle can be acquired and recorded depending on the sampling rate.

For the max. possible data volume of 4060 bytes, the maximum cycle time (timebase) is 1.4 ms. In the following table, you will find reference values for the relation between cycle time and the max. transferable data volume per cycle. If you require additional values, especially if several devices are connected in a Flex ring topology, iba recommends using the simulator integrated in ibaPDA, see chapter Telegram size calculation with 32Mbit Flex.

The following data types are supported: BYTE, WORD, DWORD, INT, DINT, FLOAT and DOUBLE in Big/Little Endian format. These data volumes represent the limit values for the overall data volume on a Flex ring that can be transferred via an FO link.

Cycle times in the Flex ring topology

ibaPDA automatically detects the devices in the Flex ring topology and determines the max. possible sampling rate, depending on the type and the number of devices.

The devices in the ring topology are addressed via the rotary switch for the device address.

The individual devices in the ring can work with different cycle times. However, these cycle times must be an integer multiple of the smallest cycle. Example: Device #1 operates with a cycle time of 0.5 ms, device #2 with 1 ms, device #3 with 4 ms, etc. If the maximum data rate has been exceeded, ibaPDA issues an error message indicating that the timebase must be increased or the data volume lowered.

The calculation of the maximum data volume depends on the fastest device in the ring topology. This means: If you increase the cycle time of slow devices in the ring topology, this does not mean that a higher volume of data can be transferred. The data volume can only be increased if you increase the cycle time of the fastest device.

For more information about data volumes in the Flex ring, see chapter Telegram size calculation with 32Mbit Flex.