Rockwell Automation 2100-GK61 DeviceNet to SCANport - Manual (Page 110)

Publication 2100-UM001B-EN-P – January 2001
6-18 Using DeviceNet Explicit Messaging
Each of the data fields in the transaction header is one byte in length.
The table below details the information required:
Data Field Description
TXID Transaction ID — when the processor creates and downloads a request to the scanner, the processor’s
ladder logic program assigns a TXID to the transaction. This is a one-byte integer in word 31, with a range
of 1 to 255. The scanner uses this value to track the transaction to completion, and returns the value with
the response that matches the request downloaded by the processor.
COMMAND For each download, a command code instructs the scanner how to administer the request:
0 = Ignore transaction block (block empty)
1 = Execute this transaction block
2 = Get status of transaction TXID
3 = Reset all client/server transactions
4 = Delete this transaction block
5-255 = Reserved
STATUS For each upload, the status code provides the processor with status on the device and its response:
0 = Ignore transaction block (block empty)
1 = Transaction completed successfully
2 = Transaction in progress (not ready)
3 = Error — Slave not in scan list
4 = Error — Slave off-line
5 = Error — DeviceNet port disabled or off-line
6 = Error — Transaction TXID unknown
7 = Unused
8 = Error — Invalid command code
9 = Error — Scanner out of buffers
10 = Error — Other client/server transaction in progress
11 = Error — Could not connect to slave device
12 = Error — Response data too large for block
13 = Error — Invalid port
14 = Error — Invalid size specified
15 = Error — Connection busy
16-255 = Reserved
PORT The DeviceNet port used by this message. The port must be zero (Channel A) on a 1747-SDN scanner.
SIZE The size of the transaction body in bytes. The transaction body can be up to 29 words (58 bytes) in length.
If the size exceeds 29 words, an error code will be returned.
SERVICE The service attribute contains the DeviceNet service request and response codes that match the
corresponding request for the TXID. Service Codes vary for each DeviceNet object. Appendix C details
available service codes referred to as “Common Services” for each object.
MAC ID The DeviceNet network address of the slave device where the transaction is sent. This value can range
from 0 to 63. The port and MAC ID uniquely identify the target slave device. The slave device must be
listed in the scanner module’s scan list and be on-line for the Explicit Message transaction to be
completed.