Reading arrays of double from S7 with OPC & Datasocket

[Javier]

Hi friends:

We are developing an application with a S7-315-2DP PLC and a PC with a PCI1500PFB. We use the OPC server from Applicom. We read the data very quickly with the datasocket (arrays of boolean, arrays of doubles ...and so on, and a very big amount of data over 100 ms) but when we try to write arrays datasocket faield and we have to write item on item and the speed decrease. For intance, if we try to write doubles ( 50 items) the refresh period is over 5 seconds ( some times more since we launch the data and we read the same data on the PC). Perhaps we failed configuring the OPC but there isn´t many things to configure, perhaps the problem is the board configuration .. I don´t know.

We
try to find some examples that write an array of doubles on one time but..


Thank you for yours answers.


Javi

[Hokie]

Hi Javi,

I'm not aware of any known issues writing to the Applicom OPC server. In LabVIEW there isn't anything special you need to configure to be able to write arrays of doubles through DataSocket. You can test this by using the DataSocket Server Manager, make a new member that is an array of doubles, and try reading and writing to that member. You may also want to check to make sure the data member the OPC server is expecting is an arry of doubles and not an array of singles or integers.

[Rafa 601]

Hola Javi,

We have found the same problem. We are using the latest version of DataSocket and we could not write any array of data to the OPC Server. I was trying to get the Applicom OPC server specs, maybe it does not accept any array of data. Could you discover something new?

Thanks,

Rafa

[GuillermoP]

Hi guys,

Have a look at KB 2MKBB3BH. Maybe the problem is the same: OPC server that doesn't publish array data type.
If you've found any other OPC Server that does publish it, please write back to NI in order to update that KB.

Regards,
GuillermoP

[Shan Pin Koh]

I encountered problems writing to a Contrologix PLC at the same speeds that you're doing and I do notice that the write would occur (without errors) and the PLC may not see the bit change until much later.

The Write VI completes and the bit changes a few ms later. I've called in for tech support and they said that this is how things happen. The workaround that I've found to be helpful is to write to 2 bits instead of just one and the write occurs quicker.