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 amount and the sampling rate can be flexibly customized. The data amount transferred per cycle depends on the sampling rate. Generally, the following applies: The less data are transferred, the higher is 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 of 2 ms to 10 µs. The maximum sampling rate also depends on the acquisition device and can be found in the device manual. In ibaPDA you can select even smaller 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 in ibaPDA a subsampling is carried out. Redundant data is discarded by ibaPDA.

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

With the maximum possible data volume of 4060 bytes, the cycle time (timebase) is up to 1.4 ms. In the following table, you find reference values for the relation between cycle time and the max. transferable data amount per cycle. To acquire further samples, especially if several devices are connected in a Flex ring topology, iba recommends using the simulator integrated in ibaPDA, see chapter Calculation of the telegram size with 32Mbit Flex.

Timebase	Max. data amount
1.4 ms	4060 bytes
1.0 ms	3100 bytes
0.5 ms	1540 bytes
0.025 ms	64 bytes

The following data types are supported: BYTE, WORD, DWORD, INT, DINT, FLOAT and DOUBLE in Big/Little Endian format. These quantities each represent the limit values for the total amount of data on a Flex ring that can be transferred via a fiber optics link.

Cycle times in the 32Mbit 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 have to be an integer multiple of the smallest cycle. Example: Device #1 works with 0.5 ms, device #2 with 1 ms, device #3 with 4 ms, etc. If the max. data rate is exceeded, ibaPDA issues an error message that advices you to enhance the timebase and decrease the data amount.

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

For more information about data allocation in a 32Mbit Flex ring, see chapter Calculation of the telegram size with 32Mbit Flex.