What is wrong with my FB? If anything.

Hello all,
I have created a new fb but for some reason when I loaded it into the PLC and attempted to monitor the block it is not outlined showing that it is working. Instead of the normal hilight, all I see is a dotted line for the outline of the block. All this fb is doing is parsing a string and writing the results into a db. It also does some sequencing functions but nothing major. This is what I have done up to this point with it. I created an instance db and associated it with this fb. Both have been saved and downloaded into the controller. Everything monitors and checks out. I can even monitor the fb that I created. I have also added logic into the fb and simply set a bit from the fb and monitored it in a vat table to verify that the block is working. But it just doesn't look right on the outside when I monitor. I have not been able to "turn on" this logic yet because it can't be used during normal operation of our plant. Can anyone tell me why this block doesn't hilight when I monitor it. I have done all of this before and it has never looked like this. Sorry if I have rambled in this question. Thanks for the help.

Siemens blocks return a block result (passed out of the ENO). If the block result is false (say an error occurred inside the block), the ENO will be false and the ladder logic following the block will be false as well as the block outline being not highlighted. Note that the rung connection leading up to the block will be highlighted if the logic indicates so. If you do not wish to use the block result mechanism and always return with ENO true, simply put the following code as the last two statements in your block. Don't perform any BEU's half way through the block either.


Your block call looks like below ?

I had this type of problem one time and found that I forgot to call the block. I had a FB calling another FB and just forgot to add the new FB after creating it.

thanks guys. the save at the end of the fb did the trick. i have seen these networks in alot of fbs in the past but just didnt know why they were there. would the fb have functioned normally if i hadnt added this. i was not going to make any other logic dependent on the eno from this fb.

John21 said:

would the fb have functioned normally if i hadnt added this.

Click to expand...

Yes.