Welcome, Guest
Username: Password: Remember me
  • Page:
  • 1
  • 2

TOPIC: Long scantime plcthreat

Re:Long scantime plcthreat 13 years 8 months ago #831

  • Maden
  • Maden's Avatar
  • OFFLINE
  • Expert Boarder
  • Posts: 86
  • Karma: 0
Hi Claes,

I tried to change the value of the ScanInterval (e.g 10, 50) for a Modbus_Module that handles the ReadCoils function, but it seems to use always the value 1 (module scantime = thread scantime), no matter what I put there.

Any ideas what could be wrong?

Ondrej
The administrator has disabled public write access.

Re:Long scantime plcthreat 13 years 8 months ago #832

  • claes
  • claes's Avatar
  • OFFLINE
  • Platinum Boarder
  • Posts: 3170
  • Thank you received: 497
  • Karma: 133
Hi Ondrej,

Yes, you are right. A read request is slipping out every scan. I have a fix for it and can build a patch if you tell me which platform you are using.

/Claes
The administrator has disabled public write access.

Re:Long scantime plcthreat 13 years 8 months ago #833

  • Maden
  • Maden's Avatar
  • OFFLINE
  • Expert Boarder
  • Posts: 86
  • Karma: 0
Hi Claes,

I'm using the 32bit Ubuntu platform. Is it enough to substitute just the runtime package or do I need to reinstall the whole development package?

I use the different scan intervals as a workaround for a problem with my IO card. This card does not handle very well 2 consecutive ModBus requests very close to each other. So I would like one Modbus_Module to send requests with a certain delay with respect to another. Can that be achieved without using different scan intervals?

Ondrej
The administrator has disabled public write access.

Re:Long scantime plcthreat 13 years 8 months ago #834

  • robert
  • robert's Avatar
  • OFFLINE
  • Gold Boarder
  • Posts: 178
  • Karma: 7
Hi Ondrej !

You just need a new library (libpwr_rt.a), which I guess claes will fix for you. On the Modbus_TCP_Slave-object you can set the SignleOp-attribute to 'true'. If so, there will be only one operation at a time. Se the ResponseTime to the time you will have to wait for a response. If you are using many operations this will however be very slow and the scan-time of the plc-thread needs to be high to avoid slip.

/Robert
The administrator has disabled public write access.

Re:Long scantime plcthreat 13 years 8 months ago #835

  • claes
  • claes's Avatar
  • OFFLINE
  • Platinum Boarder
  • Posts: 3170
  • Thank you received: 497
  • Karma: 133
Here is the modbus interval patch for ubuntu. Unpack an copy libpwr_rt.a to $pwr_lib on on the development station, and force a build of the node.

[url]files/tmp/pwrrt_4.7.0_patch01_ubuntu.tar.gz[/url]

/Claes

Post edited by: claes, at: 2010/07/05 07:34
The administrator has disabled public write access.

Re:Long scantime plcthreat 13 years 8 months ago #836

  • Maden
  • Maden's Avatar
  • OFFLINE
  • Expert Boarder
  • Posts: 86
  • Karma: 0
Hi Claes,

the patch seems to work, I have to test some more though.
Thanks for this quick fix.

Ondrej
The administrator has disabled public write access.
  • Page:
  • 1
  • 2
Time to create page: 8.346 seconds