time stamp problem on fielpoints

[karen122]

I use a FP1601 with 8 other modules.

I configured it with fieldpoint explorer 3.0.1 and firmware version is 4.17.

I want continuous acquisition so in the channel configuration I unchecked "update on change" and set update rate to 100ms.

My problem is that the refrech is done only when the value changes so it's still "update on change".

THis is a big problem as during an acquisition, when the value is fixed, I have only one value.

Could you tell me if there is something more to configure ?

thanks in advance.

Karen

[Khalid]

Hi,

Which VI are you using to do the reads?  FP Read (Poly) should get the value each time even when there's no change in value.. though the 'timestamp' will not change (since the value hasn't changed). 

Can you post a test VI to clarify further?

-Khalid

[Kerouac]

Hi,

First, FieldPoint Ethernet network controllers only send data to the host computer on change. The service (part of FieldPoint software installed in the controller) is running and is detecting the changes publishing the data to the host, it polls the channels as fast as it can. There are a number of things that contribute to the speed of that polling, namely anything that uses up processor time. Here is a list of things that can use up processor time: how often the data changes (or how much needs to be sent), the modules update rate (this can affect how often the data changes), network traffic, the number of channels to poll, router, switch, hub, cable, 10/100 MB/sec network speed...

When editing an I/O channel in Fieldpoint Explorer, the Update on Change is only meaningful when you are using a Serial network module. It is not your case. It does not affect the amount of traffic between the server and the module. It affects whether the server sends new data to the OPC Client that is asking for the data. One thing to note is that if the OPC Clients asks for the data in a different way than you have the Update On Change set, then it will override your IAK file's setting.

On the OPC client side, you can use the LabVIEW VI - FP Advise. The Advise Rate input tells how the FP Advise function polls in the background the module at a set interval until there is a change. Once a change in value is detected, the FP Advise function returns the changed value to the FieldPoint Server. The Update on Change input tells that the FieldPoint Server is still polling at the Advise Rate, but the FieldPoint Server will only return data to LabVIEW if it determines it received a value different from the current value.

Hope this helps.

Regards.

Matthieu G.

[karen122]

Hello,

Thanks for your answer Khalid.

I use an OPC server with bridgeview 2.1 where I define some tags.

The problem is that the tags coming from the fieldpoints are not well time aligned with the other tags.

I will try to run a VI with bridgeview and read the memory just to confirm.

[Khalid]

In the OPC Client (BridgeVIEW in your case), there should be a setting to read the Server synchronously or asynchronously.  Setting this to Synchronous should poll the Server and get the value even when it hasn't changed. 

I now this setting exists in LabVIEW-DSC, the successor of BridgeVIEW, under Server Browser. 

Regards,

-Khalid

[karen122]

Hello Khalid,

I checked the system and there is no option concerning synchronisation in BrigeView.

What  I've seen is that inside the fieldpoint explorer, if we have a look to the time stamp,when the value is refreshed , sometimes it happens that the times stamp is refreshed with 10 sec delay and the next refresh value is the good one.

This explains that sometimes we have the delay on our acquisition.This happens only when the opc server is launched and the test is started.

We tried to set the time server IP address to 0.0.0.0 to use the internal clock of the FP module and then it was ok.

But now the clock has each day a new delay with the Host one and we have to resynchronise the 2 clocks every day!