Page 259 - Sensors and Control Systems in Manufacturing
P. 259
Networking of Sensors and Contr ol Systems in Manufacturing
4.10.2 Carrier-Band System for MAP Protocol 219
Another type of MAP network makes use of a carrier-band
approach, which uses somewhat less expensive modems and inter-
face units and does not require heavy duty cable (Fig. 4.15). For a
small factory, a carrier-band version of MAP can be much more
cost-effective. The carrier-band communication can also achieve a
high data rate of 5 to 10 Mb/s, but only one channel can operate on
the cable at a given time. A single channel is used for both trans-
mission and reception.
4.10.3 Bridges MAP Protocol
It is possible to use devices called bridges to link a broadband factory-
wide communication network to local carrier-band networks
(Fig. 4.16). The bridge transforms the message format provided on
one side to the message formats required on the other. In this sense, a
bridge transforms one operating protocol to another.
Equipment Equipment
unit unit
∗ ∗
Carrier-band
cable
Bridge
Broadband
system
∗ ∗
Computer Computer
FIGURE 4.15 Carrier-band system for MAP protocol.
