Rockwell-automation 1775-KA PLC-3 Communication Adapter Module User Ma Instrukcja Użytkownika Pobierz pdf (Strona 86)

Message Procedure Commands

Chapter 6

68

the value of the expression is false (0), the embedded command is not

executed. The embedded command may be any of the available

commands except another IF or an ON_ERROR.

Figure 6.1 demonstrates the combination of a label, a GOTO command,

and an IF command to construct a simple loop that assigns the integers 0

through 7 to successive words in binary file 50.

Figure 6.1

Example

of Looping

NUM = 0

LOOP: $B50:(NUM) = NUM

NUM = (NUM +1)

IF (NUM .LE. 7) GOTO LOOP

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The ON_ERROR command specifies what action should be taken if an

error is encountered during execution of the message procedure. The

ON_ERROR command is not executed sequentially in the procedure; it is

executed only when an error occurs.

Table 6.A illustrates the format of the ON_ERROR command. The

ON_ERROR command contains an embedded command that is executed

when an error occurs.

The ON_ERROR command applies to all other commands between itself

and the next ON_ERROR command. For example, consider the following

sequence:

ON_ERROR Command

1 2 ... 81 82 83 84 85 86 87 88 89 90 91 ... 238 239

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