Page 266 - Sensors and Control Systems in Manufacturing

Networking of Sensors and Contr ol Systems in Manufacturing
In addition to the reflection center of the main hub, the universal 225
memory network includes smaller subsystems called shared memory
interfaces (SMIs), which make it possible for computers based on dif-
ferent bus architectures (e.g., SELBus, DEC BI, Multi Bus, and VME,
or other selected buses) to communicate via the reflection bus. Each
host computer is attached to the reflection center by a bus-interface
circuit card, which translates the read and write transfers of the host
computer to and from the reflection-bus standard. This translation
centers around the ordering of bits and conversation used by various
vendor architectures to a common strategy required by the 100-ns
cycle time of the reflection bus.
The standard memory interface enhances the modular nature of
the network. It provides computer memory access to processors of
lower cost and enables a large number of workstations to be sup-
ported from one reflection center. For example, one reflection center
can support up to 12 SMI memory interfaces, each with the capacity
to support between 8 and 16 workstations, depending on local hard-
ware configurations. Multiple reflection centers can be interconnected
to support even more workstations.

4.13 Satellite Sensor Network
The Satellite Sensor Data Service uses a spread spectrum technology,
which is optimized to enable the reliable receipt of large numbers of
simultaneous transmissions from multiple users in a distributed sen-
sor network. The system consists of a field device containing a
modem, the satellite relay system, network data processing equip-
ment, a view data portal, and a data analysis tool.
The process unfolds as follows:
1. A one-way message containing the GPS location and sensor
data is sent from a field device to the low-earth-orbit satellite
network. The field device sends multiple messages to increase
the reliability of message receipt to 99.99 percent or higher
with correct installation in the coverage area.
2. The “bent-pipe” satellite relays messages to a ground station
equipped with a Satellite Sensor Data Service decoder. Redun-
dant messages are filtered and the customer only pays for the
first message received. The message is decoded and for-
warded to the Asset-View data portal.
3. Message data is made available to the end user via the Inter-
net, voicemail, e-mail, or text.

Satelite Link of Global Network transmitting data of businesses
and individuals, Fig. 4.20. The coverage area of the message data is
illustrated in Fig. 4.21.