wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

Communication Aspects of IEC 61499 Architecture 55-5
START
RUNSTOP
COLD
WARM
STOP
E_RESTART
“RUN”
“STOP”
INIT INITO
REQ CNF
IND
SWITCH2
QI QO
LABEL1 OUT
LABEL0
IN
RS_GATE
EI EO0
EO1
E_SWITCH
G
DT
INIT INITO
REQ IND
PERIODIC
START EO
STOP
E_CYCLE
DT
LOGIC
INIT INITO
NEW CNF
REQ CR
LIGHTS
MODE LED3
LED2
LEDS
INIT INITO
REQ CNF
LEDS4
LED3
LED2
KNOB
1 QI QO
W OUT
“TIME”
t#250ms
TYPE
IVAL
MODE
INIT INITO
REQ IND
SWITCH3
LED1
LED0
BITN
LED1
LED0
C0
C1
1
QI
QO
“ALL, CHASE_UP, CHASE_DOWN”
CHOICES
OUT
I
Controller
START STOP TIME MODE
ALL
CHS_UP
LED3
CHS_DOWN LED2 LED1 LED0
FIGURE 55.2
between them.
FB diagram shows the distribution of functionalities between blocks and event and data flow
LOGIC
LEDS
This block contains the control logic of the system. Given the current operation mode (as
a number at the MODE data input), it produces a new combination of four values at the
LED0 … LED3 data outputs upon the input event REQ
Interface to the LEDs. Upon receiving the REQ input event refreshes the LEDs with the
values of the LED0 … LED3 data inputs
Besides, there are three more service FBs:
START
RS_GATE
PERIODIC
Emits an event at its COLD event output upon physical restart of the device executing
this application
Trigger, emitting events corresponding to START and STOP commands of the start/stop
switch
Upon activation by the start event generates events periodically with the frequency determined
by its DT data input. In our application, this event is connected to the LOGIC FB
causing the next lights pattern generation
The IEC 61499 FBs are great for fast prototyping and simulation. Thus, in order to test the control
logic, the developer can substitute interfaces to physical peripherals by instances of FB types that emulate
those peripherals using human–machine interface elements, as illustrated in Figure 55.3. As long as
the interfaces of two FB types are the same, this operation is very simple and preserves the structure of
interblock connections.
Thus, the RUNSTOP FB is now implemented using the RADIO_BOOL FB type that creates and
listens to the radio button element with two values: RUN and STOP. As a result of the FB-type substitution,
the application logic can be initially tested without having the peripherals connected. The reverse
substitution will produce the fully deployable application.
© 2011 by Taylor and Francis Group, LLC