OPERATION
Copyright 2007
5-5
S SC150e HARDWARE REFERENCE
5.5.1 Message Contents
The smallest S SC150e Network message packet consists of 82 bits. This
basic message format contains five fields: Source ID, Age, Control, Data Address, and
Data Value. The message can be described as follows:
Table 5-1 S SC150e Message Contents
START ID AGE CONTROL DATA
ADDRESS DATA
VALUE
1
8+P
8+P
1 1 1
RES INT RTY
5+P 8+P 8+P
8+P 8+P 8+P 8+P
For every 8 bits of data in the message there is a parity bit attached.
SOURCE ID
This 8-bit field contains the node ID of the originating node. Value ranges from 0 to 255,
so there can be 256 nodes on the network ring.
AGE
This 8-bit field increments by one as a message passes through each network node. If the
age ever exceeds 256 (the maximum number of nodes on the network), the message is
removed from the network.
CONTROL BITS
RES - Reserved.
INT - When this bit is set it signals an Interrupt Message.
RTY - Retry message used only in error correction mode (PLATINUM.)
DATA ADDRESS
This 21-bit (A[22:2]) field contains the relative S SC150e memory address.
Bits A0 and A1 are always zero for a longword boundary.
DATA VALUE
This 32-bit field contains the data value in S SC150e memory that is
currently being updated around the ring. When the PLUS mode is enabled, data size may
vary up to 256 bytes or 1024 bytes depending on the option selected.
5.5.2 Protocol
BURST MODE
BURST
Mode is the normal protocol for S SC150e. The BURST mode is
enabled by setting CSR2[12] off, and CSR2[14:15] ON. The BURST
Mode protocol
allows each node to continuously transmit messages onto the network ring. This mode
uses a 4-byte fixed-length message packet for data transfer.
PLATINUM MODE
The PLATINUM mode is BURST mode with error correction enabled. PLATINUM
mode is enabled by setting CSR2[12] OFF; CSR2[14] ON; and CSR2[15] OFF See the
Protocol Mode Definition table in appendix C, page C-3.
Summary of Contents for SCRAMNet+ SC150e
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