8.5.1.2.2 Transaction Frame Examples

Transaction frames are created using the frames discussed in the previous sections. The following sections outline all of the ways transaction frames are created using the individual frames. The CRC values in the examples are correct and are used to verify the customer CRC algorithm. The CRC is verified by the device with every received command frame and the command is not executed unless the CRC is valid. Command Frames fall into two general categories:

1. Write command frames that do not generate any response frames
2. Read command frames that generate at least one response frame.

The REQ_TYPE field in the Frame Initialization byte determines the category to which a command frame belongs. Category 1 contains the Single Device Write, Stack Write, Broadcast Reverse direction, and Broadcast Write request types. Category 2 contains the Single Device Read, Stack Write Read, and Broadcast Read. The number of response frames generated by the Category 2 command frames depends on the number of devices addressed by the command frame. In the case where more than one response frame is received in response to a single command frame, each response frame is a complete frame containing the Frame Initialization, Device address, Register address, Data, and CRC bytes. A single device does not respond with more than a single response frame in response to any single command frame. Figure 27 illustrates all of the different command and response frames.

Figure 27. Transaction Frame Structures