Visa communication

[vijtin]

Hiii

I am using VISA write.vi & VISA read.vi for writing & reading data from device based on RS232 TO 485 Modbus protocol.

My communication is working properly & i ma getting data perfectly.

My question is:

Is there any relation between VISA operation & OPC server during above communication?

vijtin

[Hillman]

Hi Vijtin,

Thanks for your post and I hope your well.

I am glad your setup is working well for you.

Why are you asking this question?

The modbus protocol can be used to link certain devices to OPC clients.

The Virtual Instrument Software Architecture (VISA) is a standard for configuring, programming, and troubleshooting instrumentation systems comprising GPIB, VXI, PXI, serial (RS232/485), Ethernet, USB and/or IEEE 1394 interfaces. NI-VISA is the National Instruments implementation of the VISA I/O standard. It provides the programming interface between the hardware and application development environments such as NI LabVIEW, LabWindows/CVI, and Measurement Studio for Microsoft Visual Studio.

The National Instruments OPC Servers provides a single consistent interface to communicate with multiple devices, saving you from learning new communication protocols or spending time understanding new applications. The combination of NI OPC Servers and LabVIEW provides a single platform for delivering high performance measurements and control to both new and existing industrial systems. NI OPC servers connect through the OPC client in LabVIEW Datalogging and Supervisory Control (DSC) Module to enable you develop a full fledged HMI/SCADA system with PLCs, PACs and smart sensors.

So in summary, if you want to share your data from the modbus data to other OPC devices - then yes they can be linked. But if you've not configured anything then - then no. And VISA isn't used for OPC operations. 

Hope this helps, 

[vijtin]

Hii James,

Thanx for reply.

I am developing 2 different softwares for RS232 TO 485 MODBUS based communication.

one is based on DSC module & another is based on VISA. Both are working as per my requirement.

So in case of DSC, OPC serever comes into picture but i just want to confirm for my knowledge that incase of VISA based communication whether OPC server comes into picture or not?

vijtin

[Hillman · Accepted solution]

Hi Vijtin,

Thanks for the reply.

I do not believe this will come into the picture.

Because,

OPC Servers
The following drivers can be purchased separately, in the Industrial Automation OPC Servers CD, for use with LabVIEW, the DSC Module, LabWindows/CVI, and Measurement Studio.

Hope this helps,