Rockwell Automation 2755-SNx Adaptascan Bar Code Readers - Manual (Page 243)

12–22 Communicating with a PLC-5 Processor on a DeviceNet Network using Explicit Messaging
Publication 2755-6.8
For each upload, the status code provides the processor with status
on the device and its response.
Status Code Description
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 offline
5 Error – DeviceNet port disabled/offline
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
•
TXID (transaction ID) – When you create and download a
request to the scanner, the processor’s ladder logic program
assigns a TXID to the transaction. This is a one-byte integer in
the 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. The
ladder logic program monitors rollover and usage of TXID
values.
•
size – The size of the transaction body in bytes. The transaction
body can be as many as 29 words (58 bytes) in length. If the size
exceeds 29 words, an error code will be returned.
•
port – The DeviceNet port where the transaction is routed. The
port can be zero (Channel 1) or one (Channel 2).
•
MAC ID (node address) – 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 attributes coupled
together identify the target slave device. The slave device must
be listed in the scanner module’s scan list and be online for the
Explicit Message transaction to be completed.
•
service – For each Explicit Message Request and Response, the
service attribute contains the service request and response codes
that match the corresponding request for the TXID.
service
port
TXID cmd/status
size
MAC ID
Transaction Body
(29 words)
word 0
word 1
word 2
Transaction
Header
(3 words)
word 31
15 0
One word = two bytes = 16 bits