CompoBus/D Communications Card Operations | Chapter 5 | |
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5-2 Message Communications (DeviceNet Explicit Messages)
There are two types of CompoBus/D communications: Remote I/O and message communications. This sections explains CompoBus/D Communications Card message communications. With message communications, specific instructions (SEND, RECV, CMND, and IOWR) are used for reading and writ- ing data between Master and Slave Units.
HMessage Communications Operations
Message communications enable data to be exchanged as required between nodes (i.e., between Masters or between Masters and Slaves) on a CompoBus/D Network. For example, the accumulated data from a given PC can be read from another PC, and constants from various Slaves can be changed from a PC. To use message communications, however, both nodes involved in the data exchange must support message communications.
Message communications function
Reading Inverter output current
Note:
HTypes of Message Communications
CompoBus/D message communications are broadly divided into the two categories described below. Of these two categories, the Inverter’s CompoBus/D Communications Card supports explicit mes- sages.
•Explicit Messages
Explicit messages are defined by DeviceNet. The class, instance, and attribute are specified for executing message communications. The messages are the same for all Inverter products, so mes- sages can be exchanged in the same way with masters made by other manufacturers.
•FINS Messages
Messages can be exchanged using FINS commands between CompoBus/D nodes (Masters and Slaves) that support FINS messages. (FINS commands are actually sent and received using Device- Net explicit messages.)