Profibus

Hi,
I need to send data from Siemens PLC S7-CPU313 to Roboter PC through Profibus. There are about 2000 words to be sent and it takes about 30sec. I send the data with SFC15. Is it possible to send the data faster? Does it matter if the datablock consist of MWs oder MBs oder Bytes/Words/Doublewords in DB? Each time I send 32 words.

Martin

max is 32 bytes not words.

To send 2000 bytes (or 4000 if 2000 words was correct) you would I presume be doing in chunks of 32 bytes at a time, I would also presume you are losing a byte, to identify which block of data you are sending.

What format it is in the DB doesn't matter, as long as the recieving system knows the order and reads them in the correct manner, i.e a floating point number would take 4 bytes.

I would presume the speed would depend on the PLC scantime and the response speed of the PC, expecting some sort of handshake from the PC and presuming the PC would respond within the next scan, the minimum speed would be (2000/31)*(scantime*2).

The slow speed perhaps as well could be the fact that the PLC is a slower variety.

The only ways of speeding up I can think of is upgrading to a faster CPU or get the PC to read the data via ethernet, which is again upgrading.

I'm not an expert on this type of profibus usage so perhaps someone else would have a better solution.

PeterW said:

max is 32 bytes not words

Click to expand...

are those data consistent or not? How many inconsistent data can we write throug profibus? Hand how do we do it?

It is possible to transfer up to 64 words using consistent messages. True, the original S7s could only send 16 words as consistent data but a couple years ago Siemens upgraded there Profibus DP capabilities. It is common to access our motion controller using 3 consistent data areas of 32 words for status, 64 words for writing data and 64 words for reading data. The through put is much higher than just using 16 words in and 16 words out for 8 axes.

The largest consistent data area you can have is 128 bytes and you can have more than one consistent data area.

Until Siemens upgraded their Profibus DP the best Profibus masters were PCs with SST or Hilscher cards. The best PLC Profibus DP master were the AB PLC5 with SST card or the TI505. These two PLCs were the only PLCs that could have these large consistent data area. This must of been embarrassing to Siemens.

Hi,thanks for your replay. But how can I use more then 32Bytes? Is there a SFC to transfer the data to DP(SFC 14 and 15 can only 32Bytes)? How can I define the data area ie. 64 words? My PLC communicates with a KUKA robot PC througs Profibus. In Simatic Manager I define hardware as a PLC CPU 313 and KUKA DP Slave on a Profibs. In this slave I put two universal modules(one for IN, second for OUT). In those modules I define area for Profibus. If I select data as a consistent data only 16 Words as input and 16 words as output kann be selected. Should I download new GSD files for KUKA slave or to change something in Hardware Configuration?

Martin

I am using one of Peter's controls and we are using SFC14 & 15 with WINAC RTX. I know that before we used a CP343-5 Profibus module and we used different FC's for this module. Make sure the FC's are supported in the DP module you are using.

I assume you are planning on uploading/downloading point data from the KUKA robots. I am doing something simialar with Yamaha robots. I found that I did not need to read/write all the points just the first 50. Then if needed I can copy from one point to another in the robot program.

Hope this helps

Yes, the command that allows more data to be sent is DP_SEND FC1 and DP_RECV FC2. I had to look these up in my Berger book. We used these with the CP342-5

Where in the world are you guys getting your info-

Especially you Peter-

Depending on the SLAVE the max is 244 bytes of send and another 244 bytes of receive.
The S7 has been able to do this from day one.




Here's a document with a good overview

http://www.acromag.com/pdf/profibus_Introduction_698A.pdf#search='profibus%20information'

Check out page 6

That is not PTO information. It is second hand info.

That data is incomplete.

I have the manuals published by PTO/PNO and we bought the Siemens Profibus DP development kit. Our second generation motion controller was the first Profibus DP slave in the West to pass the certfication on the first try. The test went so smoothly it took only two days instead of three. We know Profibus DP and how to make slave devices and how not to design Profibus DP masters.

It is possible to transfer up to 64 words using consistent messages.

Click to expand...

I don't find the word consistent in that document you posted.
I don't like the way the word consistent is used in the Profibus DP context, but I have decided to use the terminology as it comes from PTO/PNO.

Depending on the SLAVE the max is 244 bytes of send and another 244 bytes of receive.

Click to expand...

Yes, but not our motion controller. I doubt any motion controller or robot controller would. Why? I will let you ponder on that.

The S7 has been able to do this from day one.

Click to expand...

Yes, but not as 'consistent' data which is important to a motion controller and Martins robot.

Martin, you need to get the .GSD file and find out how big the largest consistent data block can be and how many you can have. You must also let us know how big the S7-313 will allow the consistent data blocks to be. Then we must figure out the largest consistent data block or message that the master and slave can handle.