Examples

[Dave1971]

Hi, Could any body give me any examples where Binary Coded Decimal would be used in a typical application. I understand that they are used in counters, but need some more information or a link please. Sorry i have found information for this. Another example, could any body put me into the right direction for finding information on Mnemonic used on a PLC. Edited May 16, 2007 by Dave1971

[gravitar]

BCD numbers are used when something electronic is geting ready to communicate numeric data with a human. They're more cumbersome than hex/binary to use for calculations, so they aren't really useful for anything else. In general terms, a mnemonic device is something that "helps you remember" something. Assembly language consists of menmonics for the actual machine instructions. "ADD" is easier to remember than 3F, for example. I suppose you could consider the PLC ladder logic instructions to be mnemonics, although there isn't any "harder to remember" machine language offered to us to use.

[TConnolly]

BCD: http://en.wikipedia.org/wiki/Binary-coded_decimal Some good info on its advantages and disadvantages. Mnemonic programming is where a text string is used to represent an instruction series. For example, in all versions of RSLogix for AB PLCs, if you double click on the rung number it will open the mnemonic editor where you can view and edit the actual instruction string that creates the ladder rung. I use both the menemonic editor and the graphic editior, combining the two is generally faster that programming with a drag and drop method only. You can open the Menmonic editor for a branch by clicking the rung near the starting corner of the branch. Most PLCs offer a Mnemonic alternative. although the actual mnemonics used will vary, even for IEC61131 languages. If you need info on how to use it in a specific PLC then provide the PLC make and model and someone can give you an answer.

[Dave1971]

Thanks for the replies. I was wondering what other methods are there to program a PLC. There are only two that i can identify. Ladder Logic Grafcet Does anybody know any more. And maybe a link to them to show the advantages / disadvantages please.

[rpraveenkum]

Ladder logic (graphical) Function block diagram (graphical) Sequential Function Chart (graphical) Structured text (textual) Instruction list (textual)