Single Channel Structure

Description of Technique

Single channel structures comprise one functional unit for the carrying out of the specific function. In order to prevent a dangerous failure in the event of fault, the correct functioning of such a system must be tested periodically or continuously monitored. If periodical testing used, then the test cycle must be in line with the fauit tolerant interval of the process being controlled. Since testing monitoring of the time base of a control system is only possible means of a second time base, single channel control systems must always be provided with a second independent time base. There must be monitoring in respect of the correctness and completeness of its performance of the individual program modules - in which the XX modules will also be included.

Characteristics and Special Features of the Technique

In the case of control systems with a single channel structure and periodical testing or continuous monitoring, at least aIl those faults will be detected for which the testing and monitoring systems have been designed; a further proportion of aIl the possible faults will be detected through the nondangerous but detectable fault reactions on the part of the control system. When monitoring techniques are used, also the effects of disturbance can be detected. The maximum latency period for faults, in the case of single channel structures with periodical testing will be given by the XX of the test cycle time and the test time.