Profibus SST card and Allen Bradley SLC500

Well, Derick (always good to start with a joke)

Googling "SST Profibus" seems a good place to begin. And what do you know? SST are a Canadian company. I'll bet you guys could even speak to one another. (Oh no, wait a minute. This is Canada, right? Oh, maybe not!)

Regards

Ken.
 
Hi Ken,

I did contact Woodhead about the SST card. I read the PDF files included with the software disk supplied with the SST cards. I found that since my experience to date was related to Allen Bradley DH+, RIO, DeviceNet etc that I was talking in another langauage to the Profibus SST rep. I am completely unfamiliar with Profibus. My questions to the rep were therefore not in the proper Profibus terminology. The tech supports response was to tell me to call Allen Bradley. Frustrated I hung up swearing to strongly oppose any further recommendations/mandates to use Profibus. Later I returned to the problem and started to teach myself slowly by reading the manuals when time is available. My specific question for you or anyone on this site is related to Multiplex and Real time Data. I can use Real time data to trigger tags for pushbuttons and indicators in my panelview programs. I have made some progress with the SST card and Profibus but I am not using my panelviews near the potential of a standard panelview program. By standard I mean a panelview connected to an SLC processor via RIO or DH+. The operator writes and reads data in the processor via the panelview. I know that in order to read/write data to the processor with Profibus panelview and an SST card that I need to use Multiplex Data. Specifically this is what I want to do now with a Profibus panelview. I want to display the data in a word in my ladder on a panelview with a profibus comm port. I want the operator to be able to enter data directly into files in my ladder from the panelview. The processor I use is an AB SLC 504 and the panelview is a panelview 1000 with the profibus comm port. It communicates with the processor via profibus cable and the SST card which is installed next to the processor. Doing this with DH+ or RIO is no problem doing this with a profibus panelview and SST card is not obvious to me yet. Any help would be appreciated.
 
I've used and added to (but wasn't the original designer) the SST profibus card in a SLC. The system I worked on controlled about 60 frequency drives so I'm afraid I might not be much help. The nice thing about profi is that it is really fast but won't be as easy to setup with a panelview as DH+ or RIO.

You will probably need to set up data tables (N files) and then use the copy comand to copy these N files to the scanner card (one instruction to read and one to write). You will be copying to and from an "M" table.

I can send you an example of how this was done with drives when I get back to work on Monday. Let me know if you think this will be of any help.

Not sure on the whole Canadians talking to each other bit. We do talk to each other don't we, wait I hope your not from Quebec.
 
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If have a SST- PFB-SLC, I am very familiar with how it works.

I didn't know there was a Profibus DP Panelview till your post. I guess there is always new stuff to learn. I read the Panelview Profibus DP documentation quickly, not thoroughly. What you need to do is to map the 16 input and output register of the Panelview into 16 of the 32 input and output registers. This is done when you load the .GSD file and configuration into the Profibus DP master. You should be able to see the data in the input registers change when the Panelview sends a new command or block of data. The first word of the 16 or 15 register that comes back is a command that lets the ladder know which data is in the other 15 registers. The ladder must then activate ladder to copy the returned data to the correct locations in the PLC.

The SST-PFB-SLC also has M0 ( output ) and M1 ( input ) registers that are accessed using COP commands. I don't recommend using M0 and M1 files for any regular transfer of data because there is a big time penalty. The Profibus DP master CPU and SLC cpu must arbitrate for access to this memory and only one processor can access M file memory at a time.

When talking to the SST guys, you can't expect them to know anything about the Panelview or its method of multiplexing data. They should be able to tell you how to load the Panelview .GSD file. They should have been able to tell you that the data will appear somewhere in the 32 input or 32 output registers or in the M files. They should have told you to use the 32 input and output register if possible because they are much faster to access than the M files. The SST guys should have told you that you don't use MSG blocks or block transfers, you only need the COP command if you are copying many words to or from the M files.

The Rockwell guys can't be expected to know anything about the SST card. They should be able to supply the .GSD file and clarify how the multiplexing occurs and that it is the PLC's ladder that must look at the command and from that determine what is in the other registers.

It is not clear to me if the Panelview is continuously cycling through all 15 or 16 blocks or if the block or command only changes when a button activates the block.

What I found disappointing is that the Panelview only transfers data at 1.5M bps. This means that all the devices on the bus are limited to 1.5M bps. There is no excuse for not supporting 12M bps since the two most popular Profibus slave interface chips support auto bauding from 9600 bps to 12M bps. Why cripple a product when it is so easy to do it right?
 
The SST-PFB-SLC also has M0 ( output ) and M1 ( input ) registers that are accessed using COP commands. I don't recommend using M0 and M1 files for any regular transfer of data because there is a big time penalty. The Profibus DP master CPU and SLC cpu must arbitrate for access to this memory and only one processor can access M file memory at a time.

Any idea of what kind of time penalty?

The system I refered to also had 6 other plc's and 8 panelviews tied together via DH+, 4 full racks of RIO with complementary addressing, 6 VFD's and 7 flex I/o racks on devicenet and about 1500 lines of code with a 130ms scan time. The speed of the profibus network was the least of my concerns! The M0 and M1 copy commands were executed each scan but I don't really know how often the data was updated, any idea?
 
130 Millisecond scan time?

Accessing M0 or M1 takes a little less that 1 millisecond if I remember right. It may be a little more for 5/04s and a little more yet for 5/03s. I would estimate about 1 millisecond for EACH access. It is much better to read many variables at once, because that is just one access, than read many variables one at a time because each move block is an access.
 
Yes 130mS. Big slow equipment and lots of it. Fortunately there wasn't any time sensitive control so it worked, ugly but it worked.

The system I refered to used one M0 and one M1 copy command each transfering 256 words of data to and from the scanner card. From your previoius post I take it that this added approximately 2mS to my scan time?

2mS doesn't seem like a lot of time to transfer 4 words in/out of 60 VFD's?
 
I didn't know there was a Profibus DP Panelview till your post. I guess there is always new stuff to learn. I read the Panelview Profibus DP documentation quickly, not thoroughly. What you need to do is to map the 16 input and output register of the Panelview into 16 of the 32 input and output registers. This is done when you load the .GSD file and configuration into the Profibus DP master. You should be able to see the data in the input registers change when the Panelview sends a new command or block of data. The first word of the 16 or 15 register that comes back is a command that lets the ladder know which data is in the other 15 registers. The ladder must then activate ladder to copy the returned data to the correct locations in the PLC.

Peter or Allscott,

Thank you both for replying. This is my first post on this site and I found your advice helpful.
My present setup is similar to what you have described. I can see data in the input registers when I am connected online with a laptop and using data monitor. I have configured the SST file and downloaded the configuration file to the SST card. Presently I can press a momentary or mantained pushbutton tag in the panelview and via the profibus SST card a input is set in my ladder. I can also do the same with an indicator light on the panelview and an output bit in my ladder. I want to progress further, specifically I want to write from my panelview a variable into a register in my ladder. For example if I wanted to track the serial number of a part the operator is running I require the operator in his daily procedure to go to the panelview and enter the part number into the panelview. This data I want to read in my ladder so that I can control machine actions. I want to be able to read the part number in a specific register (example N7:0). With a standard panelview I can write directly to this register. With a profibus panelview am I limited to the input output files?.
 

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