Safety PLC that Has FBD and Ladder?

[big_n]

Hi Everybody. I'm looking at a machine that requires a fair bit of safety programming (to meet EN954-1 CAT3 or CAT4). I want something that will let me program using both function block diagrams, and good old traditional ladder. This PLC will handle all of the machine safety requirements, and will integrate with the existing machine controls. The ladder will be mainly used for the integration portion, but will need to handle some of the safety portion as well. The FBD will be primarily used for safety. I have about 80 safety inputs, 10 safety outputs, and about 8 regular ins and 8 regular outs. I would also like to have the option of annunciation to a small, but decent, screen for basic fault diagnostics. I know that Siemens has a couple of options - looks like the CPU315F would work well (I have just started to look at them). Does anybody know of any other vendors out there with similar options? I could also use FBD's to do all of the programming as well, but I need something that will allow for a large number of FBD blocks, and have a decent library set as well. Some of the safety plc's I've seen will only handle a couple of hundred rudimentary type FDB's. I probably need about 500 or so in my logic. Any thoughts are greatly appreciated.

[JesperMP]

Hello big_n. In Siemens lingo "FBD" is the logical representation of code in AND and OR blocks. Is this what you mean ? Siemens LAD and FBD are functionally the same, it is just two different ways to look at code. Typically, people that are accustomed to FBD hate LAD, and vice-versa. So I am pussled as to why you would want to switch between FBD and LAD in the same project. It is most normal to use only one of them. I think that the "F" safety functions in Siemens F PLCs are made in LAD. Not sure if it can be viewed in FBD. I dont really understand what you mean with this.Do you mean to create a library of subroutines ? These are called FCs or FBs in S7. I am certain that you can create a library of more than 500 FCs/FBs. Or do you mean that there may be a limit to how many safety instructions that a CPU can handle ? Next month I shall have a closer look at how F is programmed.

[andybr]

The original Pilz safety PLC's used to work in the way you described. They were very similar in concept to the Siemens S5. Standard PLC functions could be handled in ladder but Safety functions were protected function blocks. Andybr