Task Configuration

The speed of the serial interfaces must be considered for the task configuration (see the section on Supported Hardware and the Communication Principle). For example, in order that, with 9600 bps at the serial bus terminal, the data can all actually be processed at this speed, the associated communication block must be active at least once per millisecond. The task that operates the block must have a correspondingly fast setting. The simplest case is when the entire PLC program runs in this fast task. If the task is set slower, then as long as the interface operates with a hardware handshake, the communication will function at reduced speed. Without handshake, data to be received can be lost.

Note

Pay attention to the K-Bus update time if bus terminals KL6xxx and bus couplers BKxxxx are used. The K-Bus update time which can be figured out in the TwinCAT SystemManager with a click on the bus coupler under I/O Configuration has to be less than the PLC task cycle time (10%-20%). If many terminals are connected to one bus coupler it may be necessary to increase the task cycle time to a minimum of 2 ms.