Curtiss-Wright SCRAMNet+ SC150e, Hardware Reference Manual

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OPERATION
Copyright 2007 5-21 S SC150e HARDWARE REFERENCE
5.11.2 HIPRO Mode
WRITE
The S SC150e network message is based on 32-bit longword data. If a host
processor is only capable of 8- or 16-bit data transactions, then the S SC150e
bandwidth is quartered or halved, respectively. For each 32-bit data transaction from the
host, two 16-bit data transactions, or four 8-bit transactions will occur on the bus each
requiring a S SC150e network write.
The HIPRO
mode was created to provide an efficient means to transmit two 16-bit data
transactions as one 32-bit network write. The first of the two 16-bit writes is written to
memory but is prevented from going onto the network. The second 16-bit write to
memory triggers the write of the 32-bit location to the network. HIPRO WRITE will not
work if Disable Host to Memory Write CSR2[8] is set, because the first 16-bit write must
be to the S SC150e memory.
NOTE
: The order of writing the shortwords or bytes into the longword boundary does
not matter. However, it is important that a HIPRO location does receive a second
shortword write if a first shortword write is initiated, or a total of 4- byte writes if a byte
write is initiated, to a HIPRO location. Otherwise, it is possible to partially write a 32-bit
location causing the data to be lost and never be transmitted.
The HIPRO mode is also effective for transmitting user-defined 16-bit data items. Two
16-bit data items may be sent as one 32-bit data item if they are consecutive and lie
within the same 32-bit address boundary, and interrupts are not being used.
HIPRO
mode is selected for those memory addresses which have ACR[4] set. HIPRO
Enable CSR2[13] must also be set. Use a non-HIPRO location write to synchronize the
HIPRO flags.
5.11.3 Loopback Modes
Each node has a Monitor and Bypass mode, Wire Loopback mode, Mechanical Switch
Loopback mode, and a Fiber-optic Loopback mode. These modes are used to check the
node’s performance and to test transmit/receive circuitry. The loopback mode routes data
which would normally be transmitted on to the network, directly back to the node from
different points.
Table 5-7 depicts the data path for the Monitor and Bypass Mode.
Table 5-8 depicts the data path for Wire Loopback Mode.
Table 5-9 depicts the data path for Mechanical Switch Loopback Mode.
Table 5-10 depicts the data path for the Fiber-optic Loopback Mode.
Table 5-11 depicts the data path for the Insert Mode.