speed of data comunication with rio/compact fieldpoint

[woutert]

How fast can a loop be between a pc and a compact fieldpoine or compact rio?

Lets say I need to transfert 200 bytes in both direction?

Can a loop time of 10 msec be realized?

What is the time limit? 1msec? 10 msec? 100msec?

What is the jitter on a tcp/ip transfert between the units if the network isn't shared.

Woutert

[pawel]

Hi

My experiance with cFP is that it is quite slow. You can forget about real time. First of all due to TCP/IP and second due to actuall slow rate between cFP and PC.

Undortunatelly I can not give you a number. I have not measured it.

cheers

Pawel

[chrisger]

hi there

here's a benchmark for a LabVIEW RT Application on a cFP 2020  target:

TCL (Time critical Loop):

 8 ch AI

 8 ch AO

 8 ch DI

 8 ch AO

some math incl.

 - scaling AI -> Publish Write

 - de-scaling Publish Read -> AO

 - a little bit of calculations

NPL (normal priority loop (NPL):

~10 Items Publish Read

~30 Items Publish Write

GUI (access via RemotePanel for Configuration)

Access to the published Items on the PC via FieldPoint OPC

Cycle Time of the time critical loop (TCL): < 10 ms

i strongly recommend LabVIEW RT 7.1, because i observed some real improvements in performance since LabVIEW RT 7.0, especially concerning the publishing. the programming requires strict usage of the RT programming techniques (TCL, NPL and subroutine FGV for datatransfer between the loops.  see the RT bookshelf for more info.).

[chrisger]

hi there

here's a benchmark for a LabVIEW RT Application on a cFP 2020  target:

TCL (Time critical Loop):

 8 ch AI

 8 ch AO

 8 ch DI

 8 ch AO

 some math incl.

 - scaling AI -> Publish Write

 - de-scaling Publish Read -> AO

 - a little bit of calculations

NPL (normal priority loop (NPL):

~10 Items Publish Read

~30 Items Publish Write

GUI (access via RemotePanel for Configuration)

Access to the published Items on the PC via FieldPoint OPC

Cycle Time of the time critical loop (TCL): < 10 ms

i strongly recommend LabVIEW RT 7.1, because i observed some real improvements in performance since LabVIEW RT 7.0, especially concerning the publishing. the programming requires strict usage of the RT programming techniques (TCL, NPL and subroutine FGV for datatransfer between the loops.  see the RT bookshelf for more info.).

[chrisger]

hi there

here's a benchmark for a LabVIEW RT Application on a cFP 2020  target:

TCL (Time critical Loop):

 8 ch AI

 8 ch AO

 8 ch DI

 8 ch AO

 some math incl.

  - scaling AI -> Publish Write

  - de-scaling Publish Read -> AO

  - a little bit of calculations

NPL (normal priority loop (NPL):

~10 Items Publish Read

~30 Items Publish Write

GUI (access via RemotePanel for Configuration)

Access to the published Items on the PC via FieldPoint OPC

Cycle Time of the time critical loop (TCL): < 10 ms

i strongly recommend LabVIEW RT 7.1, because i observed some real improvements in performance since LabVIEW RT 7.0, especially concerning the publishing. the programming requires strict usage of the RT programming techniques (TCL, NPL and subroutine FGV for datatransfer between the loops.  see the RT bookshelf for more info.).

[chrisger]

i'm sorry, i hit my keyboard to many.....

[woutert]

My experiances from the past.

In 1985 we have build using a intel 8080 3MHz a digital io interface. It used a GPIB interface and we were able to do 300 loops a second for reading 32 analog inputs, 18 analog outputs, 8 digital inputs and 8 digital outputs. The results were transfered over a GPIB interface each 10 msec.

Now almost 20 years later, using a 200 MHz 16 bit processor it is still hard to do the same.

Where is the bottleneck?