Posted 20 Oct 2016 Hello guys, I have gotten to a level where I can do a few things with an OMRON PLC. However, there's something that is supposed to be basic by now but I still don't understand it, and I will appreciate your help on this . What is the difference between the D, W and H memory areas of the PLC? And in what instances do I utilise each of them for storage of my data? Thank you. Share this post Link to post Share on other sites
Posted 20 Oct 2016 (edited) From a functional standpoint the only difference in those 3 is that the W memory area data is cleared during a restart and there are some restrictions on accessing D memory at the bit level depending on what CPU you have. In theory the W area should be used as Work (scratchpad) memory, the D area should be used for Data storage, and the H area should be used for Holding bit storage. In practice you can use them however you want in your program. Edited 20 Oct 2016 by Mendon Systems 2 people like this Share this post Link to post Share on other sites
Posted 20 Oct 2016 Thank you Dick Oestreich, That does give me a general understanding. I am used to SIEMENS PLCs and I would relate the two as follows from what I seem to understand; D..........................Data block memory W.........................Local memory H..........................The M memory Correct me if I am wrong, Thanks again. Share this post Link to post Share on other sites
Posted 20 Oct 2016 I've never even seen a Siemens PLC so I can't help you there. Share this post Link to post Share on other sites