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Ref.:
UoD_SpW-10X_
UserManual
Issue:
3.4
SpW-10X
SpaceWire Router
User Manual
Date:
11
th
July 2008
Preliminary
69
In Figure 7-9 the format of the reply to a Read-Modify-Write command is illustrated. The first byte
received by the SpaceWire router configuration logic is the port address followed by the destination
logical address. Fields which are depicted in bold text are expected values. Fields which are shaded
are optional. Note that the reply is always sent out of the same port as the command was received on.
The Source Path Address should not include the output port of the router being commanded as the
reply will be automatically sent out of the same port that the command arrived on. See section 7.6.8.
Source Path Address
Source Logical Address
Protocol Identifier
01h
Packet Type, Command,
Source Path Addr Len
Status
Destination Logical Address
FEh
Transaction Identifier (MS) Transaction Identifier (LS)
Reserved
00h
Data Length (MS)
00h
Data Length
00h
Data Length (LS)
04h
Header CRC
Data (MSB) Data Data Data (LSB)
Source Path Address Source Path Address
Data CRC EOP
First byte transmitted
Last byte transmitted
0 10 110
Bits in Packet Type / Command / Source Path Address Length Byte
MSB
Packet Type
Command
Source Path
Address Length
Source Path
Address Length
LSB
Source Path Address Length
Figure 7-9 Read-Modify-Write Reply Packet Format
Table 7-13 Read-Modify-Write Reply Packet Fields
Field Description Bytes
Source Path
Address
Optional source path addresses specified in the command packet. If no
source path addresses are specified then the first byte will be the source
logical address.
0-12
Source Logical
Address
The source logical address specified in the command packet. If source
path addresses are not used then the source logical address is the
address of the return packet.
1
Protocol Identifier The RMAP protocol identifier value 01h. 1
Command Byte Read-Modify-Write reply command byte. The packet type bits in the
command byte indicate this packet is a response packet.
1
Status The command status is returned in this field. The command status can be
command successful or an RMAP error code as defined in section 7.6.6.
1
Destination The destination logical address is set to the default value FEh as the 1