could you please help me with the syntax I have to use inside the Tag Editor window for a S7 1200?
– I have already connected to the device and this is fine. This step is successfully completed.
– Now I want to create the tags. So basically I take the 1st PS which basically has simply 2 DPEs: onOff_in and onOff_out, so quite simple.
If now I take the onOff_in and try to configure it in Ignition. Besides the Tag name and the server, I need to set the OPC Item Path, which in my case is [S71200] followed by the address and here is where my problems comes because I do not manage to set it properly. I know this variable is a boolean (I set it up in the system) and it is a data component of type: DBx.DBXy.z where:
x=1
y=0
z=0
So I set the OPC Item PAth such as:
[S71200]DB1.DBX0.0
but this seems to be wrong, because I cannot get the correct value, I changed the syntax to:
[S71200]DB1,DBX0.0 (note the comma)
but with the same result. So how is the syntax I have to set here for the address?
Thanks so much in advance,
Kind Regards,
PAtricia Mendez
I have still a pending question here, with such an address, how do I know if this is an input or output signal?. As a matter of fact I could define 2 different tags using even the same address but with the difference of being input or output. but where do I define this direction inside the address? or inside the tag editor?
That should be up to the programmer to supply the neccesary information. A DB can have a variety of tags, knowing if its an input or output can not be decided based on the address path, this need to be supplied as an tag-list from your plc programmer.
If its an output from the PLC, you want to give it read only access within ignition.
If its an input you supply to the PLC from Ignition, it should be read/write.
Then it is not a matter of address, but just a matter of access once I define the tags associated to that device. So sharing the same address I can define 2 different tags (with different names I mean) and sharing the same address. One of these tags will have read access only and the other one will have read/write access. Is this correct?
Thanks so much, Patricia
Not exactly sure if I understand what you’re trying to accomplish.
A device is ex a PLC. You can setup as many tags to that device as you like.
You can have multiple names on the same tag.
Tag1 = [S71200]DB1,X0.0 <- This can be read only from Ignition
Tag2 = [S71200]DB1,X0.0 <- This can be read/write from Ignition
2 Ignition tags, but they have the same PLC tag.
However, if DB1,X0.0 in your plc is getting written to by ur plc program, you will not have the chance to write to that tag from ignition, since usually the programs in S7 completes within 50ms. It is possible, but every program cycle it will get written to what the PLC writes.