Rockwell-automation 1775-KA PLC-3 Communication Adapter Module User Ma Manual de usuario descargar pdf (Pagina 50)

Data Highway Communication

Chapter 3

35

When the rung becomes true, the message instruction begins sending

command(s) across the Data Highway. At the same time, bits in a control

file word change their state (Table 3.B) to reflect the status of the

command. Even if the rung becomes false, the message command will

continue to send commands across the highway.

Table 3.B

The

Status of Bits in a Control File W

ord

WHEN:

the message instruction is true

the enable bit (16) is set

the latched enable bit (12) is set

the remote Data Highway module has received the message instruction

the request bit (17) is set

the 1775-KA module begins operation

the busy bit (14) is set

the operation is complete

the busy bit (14) is set

either the done bit (15) or the error bit (13) is set

the rung becomes false

the request bit (17) is reset

the busy bit (14) is reset

the enable bit (16) is reset

the latched enable bit (12) is reset

the rung becomes true a second time

either the done bit (15) or the error bit (13) is reset

5. Enter an extended address for the channel. In our Figure 3.1, we

address the module status area of memory, specify the 1775–KA

module, and a thumbwheel setting of 1.

6. Enter either a command or a command procedure. In Figure 3.1, we

entered the command procedure, PROC_A.

Data Highway Message Procedure

As already stated, the 1775–KA module has its own programming

language that consists of commands (Chapter 8). A group of related

commands make up a Data Highway message procedure. These

commands and message procedures determine what messages are

transmitted over the Data Highway.

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Rockwell-automation 1775-KA PLC-3 Communication Adapter Module User Ma Manual de usuario Pagina 50