SLC500 Cannot access Float Elements

I have a SLC5/03, 1447-L532B 16K mem
I dont know much about AB PLC but have a problem with a SLC.

I can access registers under F8:63. The problem is that I cannot access F8:63.

I am using Kepware and I used Logix500 and have register F8:63 as well as other registers above it.

Any clue to what I need to do?

If you guys need more info to help me out let me know.

It sounds to me like a Kepware configuration or optimization issue.

The usual DF1 command code to read any block of registers from an SLC-500 controller is command code 0xA2, which allows up to either 225 or 236 bytes of data in a single reply packet, depending on the protocol used.

Floating Point registers are 4 bytes each, so that's 56 or 59 F8:xx registers you can read in a single block, not 62.

I don't know how Kepserver optimized blocks of SLC-500 data. Many drivers, like RSLinx Classic, break up a long block read into multiple smaller messages behind the scenes.

Questions for you:

Which KepServer driver are you using ? v4 or v5 ?
What is the OPC client device ?
What is the lowest-numbered F8:xx register you are reading ?
Are there any error messages logged by Kepware about this problem ?
What is the OPC data quality for the F8:xx data ? Does all F8:xx data go to "bad quality" when you add F8:63, or just that one point ?

Kepware version is 4 or 5, used both.
I am using the Kep OPC client.
I am reading F8:60 to F8:70.

Kepware error:
Unable to read starting at F8:64 on device 'Channel1.Device1' [Status=0x10, Ext.Status=0x00]

For registers F8:64 and above the value is unknown and the quality is Bad. When using Kepware to read F8:60 to F8:70, which exist in the SLC, I am reading values for F8:60-63 but from F8:64-70 the value is unknown.

The Kep DF1 help file states that the problem is possibley a duplicate node or that the node cannot be found.

Very interesting !

You mentioned that this is an SLC-5/03 controller. Are you using DF1 Full Duplex or DH485 protocol, or something involving a serial/Ethernet bridge ?

Can you capture the serial data and post it ? The whole transaction would be ideal, or even just connect the computer running Kepware to another port running RealTerm or Tera Term and capture the outgoing packet.

....and I used Logix500 and have register F8:63 as well as other registers above it.

Click to expand...

Are you sure? Check the size of the F8 Data Register.

SOLVED !!!!!

Thanks Ken for the fast responses.

So I namely work with utility protocols such as DNP3 and modbus. When using an IO driver such as Kepware, if a point does not exist the value will read "unknown" and the quality will be "bad".

This was the problem. In the SLC the max word for the Float data region is to F8:67, but in Kepware I mapped F8:60 to F8:70. Because F8:70 did not exist in the SLC the data in Kepware from F8:64 to F8:70 was bad.

As you may know when using RSView32 and making an OPC connection to Linx, online with the SLC, one can only select addresses which exist. So I was not experiencing a problem when using the Linx IO driver.

Credit Lancie1 with the goal; I was ready to go into some obscure protocol and optimization investigation.

In general if you request a block of data for which any of the elements do not exist, the entire request is denied. The SLC won't just send you the elements that do exist.