Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual User Manual

Page 155

Network and Application Layer Protocols

Chapter 12

12Ć8

Table 12.A

The commands that the PLC-3 can send and/or receive, and the hexadecimal values for the

CMD and FNC bytes

Devices that

can send the

command

Command

Type

Command Name

Command

Message

(Hex)

CMD+ FNC+

Message

(Hex)

CMD+

PLC-3 or

RS-232-C

[1]

device

Basic"

[2]

Protected Bit Write

Protected Block Write

Unprotected Bit Write

Unprotected Block Read

Unprotected Block Write

none

PLC-3 or

RS-232-C

device

PLC-3

commands

Bit Writes

File Read

File Write

Word Range Read

Word Range Write

RS-232-C

device

PLC-3

Upload/

Download

Commands

Download Request

Restart Request

Shutdown Request

Upload Request

RS-232-C

device

Privileged

[3]

Physical Read

Physical Write

RS-232-C

device

Diagnostic

Counter Reset

Loop

Read

Status

Set ENQs

Set NAKs

Set Timeout

Set Variables

[1]

RS-232-C device means a computer or intelligent terminal.

[2]

The Basis" commands can be sent to any Allen-Bradley PC. These commands are sometimes called PLC/PLC-2 commands, but all

Allen-Bradley PC's can receive them. The PLC, PLC-2 family, and PLC-3 processors can also send these commands as well as receive them.

[3]

Allen-Bradley recommends using these commands for uploading or downloading only. To write or read specific words or bits use the basic"

commands or the PLC-3 commands.

STS (status)

The high nibble of the STS (status) byte is supplied by the application
layer. In command messages the STS byte is set to zero.

In reply messages the STS is used for reporting either application or
network error codes. A value of zero should be interpreted as no error
(that is, the message was delivered and executed successfully). Non–zero
status can be divided into two categories: remote errors and local errors.