What is the Allen-Bradley DF-1 Protocol?Hardware: Serial>>RS-232
Problem: Does National Instruments have products compatible with the Allen-Bradley DF-1 protocol? Solution: The short answer is yes, but read on to understand which products, and the development required. The DF-1 protocol is an asynchronous byte-oriented protocol that is used to communicate with most Allen-Bradley RS-232 interface modules. More specifically, the DF-1 serial frame composition is that of a conventional RS-232 serial frame, where DF-1 forces some of the serial parameters such as 8 data bits, no parity, and a maximum baud rate of 19200. Further, the DF-1 protocol specifies how to send data through a conventional RS-232 serial port, in order to communicate with the corresponding Allen-Bradley products. The idea of such a protocol is to declare, for example, that all DF-1 devices will reset when they receive the characters RST* in that order (this is not the case to the author's knowledge, but it expresses the idea of such a protocol). Therefore, the protocol can be implemented using any API which can access RS-232 resources; National Instruments-VISA is an example. Thus, of course, National Instruments does sell DF-1 compatible interfaces - they are just RS-232 interfaces; indeed any RS-232 port such as the native RS-232 ports found on many computers can communicate with Allen-Bradley DF-1 devices. And although the DF-1 protocol itself is not already implemented in a National Instruments product, it could be implemented in LabVIEW or LabWindows/CVI using the National Instruments-VISA API (or any other development environment which supports an API for accessing RS-232 resources). Related Links: KnowledgeBase 2QRHDEBS: What is the RS-562 Serial Communication Protocol? KnowledgeBase 1ZCBLA47: Can I Use the CAL Protocol in LabVIEW Using the NI-CAN Driver VIs? KnowledgeBase 2OKCMQ2Y: What Is the Difference Between DeviceNet and CAN? Attachments:
Report Date: 08/23/2005 Last Updated: 08/11/2006 Document ID: 3OMF064B |
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