Rockwell-automation 1769-ADN Compact I/O 1769-ADN DeviceNet Adapter Uživatelský manuál stáhnout pdf (Strana 174)

Publication 1769-UM001B-EN-P - October 2002

B-16 Explicit Messaging Application Examples

Following each command reply, the user program must MOVe a

command value of 4 hexadecimal to the appropriate M0 file word to

clear the previous reply from its buffer, making it ready for the next

command.

The following illustrates the Get 1769-ADN Status command and the

command reply:

Command (Hexadecimal) Description (High Byte/Low Byte)

0101 TXID

/Command

0006 Port #

/Byte Count

0E13 Service

/Mac ID

0001 Class

0001 Instance

0005 Attribute

Reply (Hexadecimal) Description (High Byte/Low Byte)

0101 TXID

/Status

0002 Port #

/Byte Count

8E13 Service

/Mac ID

xxxx Status Word from Adapter

1 TXID (Transmission ID) is used by the scanner to track the transaction to completion and returns the same

value with the reply. To properly track commands with their replies, this value should be incremented for

each new command sent. TXID size is one byte.

2 Command instructs the scanner on how to administer the request. “01” is the Execute This Transaction

Block command. The command data size is one byte. Refer to the 1747-SDN User Manual, publication

1747-5.8, for list of supported commands.

3 Port # is the physical channel of the scanner where the transaction is to be routed. The port # must be 0

(channel A) and the data size is one byte.

4 Byte Count identifies the number of bytes in the transaction body. The transaction body begins with

word 3 and the data size is one byte.

5 Service specifies the type of request being delivered. “0E” is a Single Parameter Read. In the reply, the

high bit of this byte is set, so 8E represents the reply to the 0E service. Service data size is one byte.

6 Mac ID is the DeviceNet network node address of the device for which the transaction is intended. The

slave device must be listed in the scanner module’s scan list and be online for the explicit message

transaction to complete successfully. The Mac ID value must be hexadecimal. In this example, the node

address of the 1769-ADN adapter is 19 decimal or 13 hexadecimal. The Mac ID data size is one byte.

7 Class is the desired DeviceNet class. “1” hexadecimal is the class code for the identity object. The class

data size is one word.

8 Instance identifies the specific instance within the object class towards which the transaction is

directed. “0001” hexadecimal is the instance of the identity object in the 1769-ADN. The instance data

size is one word.

9 Attribute identifies the specific characteristic of the object towards which the transaction is directed.

“0005” means Status. The attribute data size is one word.

1 2 ... 169 170 171 172 173 174 175 176 177 178 179 ... 203 204

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