RapidIO: The Next Generation Communication Fabric For Embedded Application

4.3. RESPONSE CLASS TRANSACTIONS

A response transaction is issued by a RapidIO end point when it has completed a request made to it by an initiating RapidIO end point. Response transaction packets are always directed and are transmitted in the same way as request transaction packets. Broadly, format Types 12, 13, 14, and 15 are considered Response class transactions. Currently, Type 12 and 14 are reserved and Type 15 is implementation defined. Type 13 is the main Response class transaction.

The Type 13 packet format returns status, data (if required), and the requestor's transaction ID. A RESPONSE packet with an 'ERROR' status or a response that is not expected to have a data payload never has a data payload. The Type 13 format is used for response packets to all request packets except maintenance and responseless writes. Maintenance requests are responded to by maintenance responses.

4.3.1. Field Definitions for Response Packet Formats

Figure 4.2 illustrates the format and fields of Type 13 packets. The field value 0b1101 in bit positions 12–15 specifies that the packet format is Type 13.

Figure 4.2. Response packet format

Table 4.3. Field definitions and encodings for all response packets

Field	Encoding	Sub-field	Definition
Transaction	0b0000		RESPONSE transaction with no data payload
Type	0b0001–0111 0b1000 0b1001–1111		Reserved RESPONSE transaction with data payload Reserved
TargetTID ...