Page 1154 - The Mechatronics Handbook

PLC1
Computer

RS-232

HMI
run DH+ PLC2
stop

DH+
Weld Controller

Devicenet

FIGURE 43.14 PLC communication example.

Development Time
PLC
Embedded

Complexity
Unit Cost
PLC

Embedded

Complexity
Cost

PLC

Embedded
FIGURE 43.15 Relative trade-offs between control
solutions. Number of Units

43.4 Conclusion
PLCs and embedded controllers are complementary technologies and, when applied strategically, they
will both provide low cost and reliable solutions to control problems. Figure 43.15 shows the relative
trade-offs between the controllers. In general, an embedded controller requires more initial development
time than a PLC for a simple system. As the system grows more complex, the embedded controller benefits

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