Update FMS comm

Hi all,
I'm trying to update an FMS connection between 2 S7-300 PLCs. What I need to do is to add new variables to communicate between the 2 PLCs. There's already a (working) connection established between the two PLCs and I want to use that connection to send some new information from one PLC to the other. I can't find any articles related to this in the Siemens Knowledgebase. Can anybody give me a hand with this? Thanks.

Hello and welcome maidamar.

Here is a link to a description of FMS used with S7-to-S7 comms:
http://support.automation.siemens.com/WW/view/en/19126317
It appears that the definition of where the data is to be taken and where it is to be placed is done with ANY pointers. In other words there is a start address (DB and Byte no) and how many bytes to transfer.
You may have to expand the relevant DBs in both PLCs and increase the number of bytes to transfer. Thats it.

Thanks for the quick answer JesperMP. I have read the article you pointed out, but it was of no help, sorry.
What I want to do is to create a new variable to communicate instead of modifying an existing one. I have created a new DB in both PLCs (with the same structure) and configured one of them as a communication variable (with a FMS index number). After adding the READ block in the ladder logic (properly configured) and running it, I get an error 0x0607, which I searched and it means "The object does not exist in the OV or GetOV doesn't run" (it's a translation from spanish so I don't know if that's right, but the error number is correct).
I beleive that only during power-up the FMS indexes are "published" on the network so others know what objects are available. I've tried putting both PLCs in STOP and then in RUN again, but the error is still there.
Thanks for reading so far
Hope somebody can give me a hint with this.