GE VMIPMC-5565

GE VMIPMC-5565
Functional Characteristics
Introduction: VMIPCI-5565 is the PCI member of the GE Fanuc
Embedded Systems’ VMIxxx-5565 family of Reflective Memory
(RFM) real time network products. The other members of the
family are VMIVME-5565, VME-compatible board, and
VMIPMC-5565, the PCI mezzanine card (PMC). All three of these
products are network compatible, and may be integrated into a
network in any combination.
This family of products allows computers, workstations, PLCs,
and other embedded controllers with dissimilar operating
systems or no operating system at all to share data in real time.
To the local node, the Reflective Memory board appears as
shared memory. Data can be written to or read from the
memory by any level of software, including the application itself.
Data written to the Reflective Memory in one node is
transported by the network hardware to all other nodes and
placed in the same address on those node’s Reflective Memory
boards. This transport of data is accomplished without the
involvement of the processors on any node. By this system, all
nodes on the network have a local copy of shared data
available for immediate access.
Product Overview: The Reflective Memory concept provides a
very fast and efficient way of sharing data across distributed
computer systems.
The VMIPCI-5565 Reflective Memory interface allows data to be
shared between up to 256 independent systems (nodes) at rates
up to 174MB/s. Each Reflective Memory board may be
configured with 64MB or 128MB of onboard SDRAM. The local
SDRAM provides fast Read access times to stored data. Writes
are stored in local SDRAM and broadcast over a high speed
fiber-optic data path to other Reflective Memory nodes. The
transfer of data between nodes is software transparent, so no
I/O overhead is required. Transmit and Receive FIFOs buffer
data during peak data rates to optimize the host computer and
bus performance to maintain high data throughput.
The Reflective Memory also allows interrupts to one or more
nodes by writing to a byte register. These interrupt (four levels,
each user definable) signals may be used to synchronize a
system process, or used to follow any data. The interrupt always
follows the data to ensure the reception of the data before the
interrupt is acknowledged.
Each node on the system has a unique identification number
between 0 and 255. The node number is established during
hardware system integration by placement of jumpers on the
board. This node number can be read by software by accessing
an onboard register. In some applications, this node number
would be useful in establishing the function of the node.
Link Arbitration: The VMIPCI-5565 system is a fiber-optic daisy
chain ring as shown in Figure 2. Each transfer is passed from
node-to-node until it has gone all the way around the ring and
reaches the originating node. Each node retransmits all
transfers that it receives except those that it originated. Nodes
are allowed to insert transfers between transfers passing
through.
Interrupt Transfers: The VMIPCI-5565 provides four network
interrupts. Any processor can generate an interrupt on any
other node on the network. In addition, any processor can
generate an interrupt on all nodes on the network with a single
register write.
In response to this interrupt register write, the sending
VMIPCI-5565 issues a special packet over the network, which
contains the command strobe, the sender node ID, the
destination node ID, and 32 bits of data. When a receiving node
detects the proper combination of destination node ID and
command strobe, it stores the sender note ID and the data in
one of four 127 location-deep FIFOs. The four FIFOs correspond
to the four interrupts. Upon storing this information in a FIFO,
the receiving node issues an interrupt to the local processor if it
has been software-enabled. The 32 bits of data stored in the
FIFO is user-definable and typically is treated as an interrupt
vector. As part of an interrupt service routine, the local
processor reads this information out of the FIFO and acts
accordingly.