You could use the PLC tutorial to learn that; anyhow, I have the link to that tutorial and a detailed explanation of the on/off latch circuit in the following article...
Paper Presentation:"Applying the Control Programming Standard IEC 61131-3 to Software Engineering"
Posted at: http://www.doylet.org/docs/simula.docAbstract:Preparing periodic batches to run updates or get reports from mainframes, requires a good understanding of the requirements of each component, to avoid the cancellation of any batch process and its resulting lost of time and resources. To improve that understanding, an industrial Programmable Logic Controller (PLC) was set to simulate a batch process; the industrial components included in the existing tutorial, were used based on their functionality, as equivalent software components.
Note:If you publish this article elsewhere, or use it as a reference, please send me the details to
FernanDoylet@yahoo.com or reply to this post.