Siemens S7 remote i/o access

Pedro64 · Oct 16, 2005

Can anyone help me i'm fairly new to siemens, i need to access some i/o from other plcs on a multiproject, the plcs are networked and have profibus, ethernet and mpi? I want to access either the inputs or alarm flags from the other plc's so that i can switch some local indicator lights on. Any pointers in the right direction would be gratefully recieved.

PLucas · Oct 16, 2005

Pedro64 said:
the plcs are networked and have profibus, ethernet and mpi?

Pedro64

Are all these PLC's S7's?

Tell us how they are already networked, do you really have all three stated above?

With this information we can give you a more specific answer. It is not too difficult to 'get' data from another PLC, the method to use will depend on how these PLC's are networked.

Paul

Pedro64 · Oct 17, 2005

Yes Paul, they are all s7s it does have all of them. It uses the profibus for the hmi's and moby's and the ethernet is so that you can access the plc's from anywhere on the local network. I'll see if i can get more info for tomorrow. I think that most of the plcs send data back to a master. I need to know how to address the i/o on the slaves.

JesperMP · Oct 17, 2005

I think that most of the plcs send data back to a master.

Maybe, but probably not.
The Moby's are probably accessing the PLCs via wireless ethernet. That means that each Moby can access any address in any PLC.
It is also possible that one PLC gathers all information, but there is no big advantage to that if you ask me.

I would look into how the original programmer has made the original project.
In the HMI projects there must be some alarm definitions. Trace these to the place in the program where you can "tap" the information you need to turn on your local alarm indicators.
The HMI's are simply polling the data, your remote PLC (where you want to add some indicators) cannot do that.
You may have to add some communication blocks in order to transmit the info back and forth between the PLCs.

Borte · Oct 17, 2005

Isn't the "Moby's" a RFID system. It's a profibus slave communicating to a "master" plc.

Are all the plc's on the same profibus network?

Cheers
Borte

JesperMP · Oct 17, 2005

Borte, you are right.
I should have read more closely. I was thinking about "Mobic" panels, not "MOBY" !

Anyway, it is still correct that Pedro64 will have to add some communication blocks (AG_SEND and AG_RECV I think) in order to exchange data via ethernet.
Profibus is also possible, but there are some pitfalls, so ethernet is probably the easiest.

PLucas · Oct 17, 2005

JesperMP said:
(AG_SEND and AG_RECV I think) in order to exchange data via ethernet.

Profibus is also possible, but there are some pitfalls, so ethernet is probably the easiest.

Yep, it is AG_SEND and AG_RECV (FC5 and FC6, FC50 and FC60).

As for profibus, there is a problem with 300 to 300 comms, 300 to 400 is OK.

Perhaps, it would be easier for Pedro64 to use unconfigured connections via MPI as he states that they are networked via MPI.

Paul

JesperMP · Oct 17, 2005

As for profibus, there is a problem with 300 to 300 comms, 300 to 400 is OK.

I could be OK to use Profibus. But if he allready has multiple profibus networks setup with one master in each (the most common setup), then it will be hairy to put everything into ONE Profibus network.

Perhaps, it would be easier for Pedro64 to use unconfigured connections via MPI as he states that they are networked via MPI.

If he allready has Ethernet on all the required CPUs then it would be a shame not to utilise it.
And I think that it will not be much more difficult than MPI to get it working.

PLucas · Oct 17, 2005

JesperMP said:
If he all ready has Ethernet on all the required CPUs then it would be a shame not to utilise it.
And I think that it will not be much more difficult than MPI to get it working.

I agree with everything that you have written there, I was thinking along the lines of using unconfigured connections on MPI, that way the hardware configuration/network configuration does not need altering within Simatic Manager. If the information is only required on one of the PLC's, then only the program within that PLC will need modifying to 'get' and 'put' the data, None of the other PLC's will need to be touched.

It will all depend on what way Pedro64 wants to go with this.

Paul

Pedro64 · Oct 19, 2005

Hi all, thanks for your useful comments. It is AG_SEND being used, i found a a data block where all the alarms are going back to and i can monitor them. What i don't know how to do is address the data block ie the data block is DB190 and i need to address the 0.7 and several others. I've tried DB190.DBX0.7 that doesn't work? Do i have to do something else?

Pete.

PLucas · Oct 19, 2005

Pedro64 said:
I've tried DB190.DBX0.7 that doesn't work? Do i have to do something else?

I can't understand why that doesn't work, can you post the part of your logic where you are addressing the DB bits?

Something like:-

A DB190.DBX0.7
= Q0.1

or

 

DB190.DBX0.7         Q0.1

-----| |-------------( )

Should be fine.

Paul

JesperMP · Oct 20, 2005

Where are you getting the "0.7" from ?
Maybe it is a case of the byte-swapping confusion that can hit one when working with S7.
Try DB190.DBX1.7 in stead.

Pedro64 · Oct 20, 2005

Paul you were right DB190.DBX0.7 does work it was a typing error i was tired at the time. Just one more problem to solve now. I'm going to use 4 AS-i 4*output modules to get my 14 outputs, i'm connecting to a CP 343-2 in slot 6 with address range I96-111 and Q96-111, in the symbol table i've found consecutive free i/o at q99.0 to q99.7 and q100.0 to q100.7. According to the electrical drawings connects to the As-i cable M3, what i'm confused about is the AS-i output module addressing, they label the addresses as slaves ie. M3 Slave 10, Slave 9 to Slave 4 are not used i'm assuming the slave addresses i need are somewhere between Slave 9 and slave 4. How do i calculate which address i need as the CP 343-2 scans +10 then +20 then +30 then repeats again for channel B? This seems greater than the address range of the module Q96-Q111?
Can you help explain this or point me to some documentation that might help.
Once again thanks for every ones comments.

Pete.

PLucas · Oct 20, 2005

Pete

I have done very little (read none) with ASi, but I do remember some points from a training course I had a couple of years ago.

Each ASi module does need to have a node address or slave address, some of these are setable by programming, some require dip switches to be set to represent the node number.

In the hardware configuration, you will then drag and drop the new ASi slaves onto the ASi Interface module, I expect that Step7 will assign the slave addresses and I/O addresses, but these should be user selectable as well, so you can then change them to what you want or just go with the system selection.

Once the new hardware configuration has been compiled and downloaded you should be good to go.

I can't really help you much more than that, there are some ASi training material on the Siemens training web site,

Point your mouse here and click

That might be of some help, but I haven't read the material.

Paul

Pedro64 · Oct 20, 2005

Yes Paul you're right about each module needs an address programing in. I've got a programmer for doing this, it's just relating that address to the addresses in the PLC. Thanks anyway, i've downloaded the material on the asi from you're link and i'll have a read tonight. Hopefully one day when i'm more experienced i can pass on my knowledge. It's great to know ther are forums like this where people are willing to share their gained experience.

Thanks again

Pete

Siemens S7 remote i/o access

Pedro64

Member

PLucas

Member

Pedro64

Member

JesperMP

Lifetime Supporting Member + Moderator

Borte

Member

JesperMP

Lifetime Supporting Member + Moderator

PLucas

Member

JesperMP

Lifetime Supporting Member + Moderator

PLucas

Member

Pedro64

Member

PLucas

Member

JesperMP

Lifetime Supporting Member + Moderator

Pedro64

Member

PLucas

Member

Pedro64

Member

Similar Topics