Bidirectional peripheral communication

The bidirectional peripheral communication provides the possibility to define a data point element as an input and as an output in the address panel. Earlier two data points had to be configured, where input and output addresses were available. This configuration is not necessary for drivers that support In/Out addressess.

There is an attribute in the original value config in order to display the transition of a DPE with an Input/Output address config when a new output value was sent. The _transition attribute displays when a value was sent but no confirmation was received yet. If, for example, a value is set in WinCC OA, the transition bit is set automatically to 1 and a confirmation is expected from the periphery.

The waiting period (default 10 seconds) can be defined via the IOTransitionTimeout config entry in the driver specific section (see also chapter [all drivers]). If the timeout elapses and no confirmation was received from the periphery, the original value is reset to the value that the periphery contains at that time. Also the transition bit is changed automatically to 0. If a confirmation is received before the timeout elapses also the transition bit is reset.

The value for the config entry IOTransitionTimeout should be two times bigger than the biggest configured poll interval to prevent the polling process from running into an timeout all the time.

Now it is possible to deactivate the transition timeout. If you set the config entry IOTransitionTimeout to 0 in the driver specific section of the config file, the original value will not be reset and the transition bit will not be used.