
Chapter 2
CIP Services and User-created Tags
46
Rockwell Automation Publication 1756-PM020F-EN-P - January 2019
4.
Add one to the instance number determined in step 3.
5.
Send the request again using the new instance value in the Request
Path.
When General Status = 00
Success
, then all the symbol instances that are
created have been returned.
See also
CIP Services and User-created Tags
Step 1: Finding user-created controller scope tags in a Logix 5000
The table following shows the format of the initial service request, which
starts with Symbol Object, Instance 0. This returns as much of the requested
data as will fit in the reply. Most controller programs require multiple
attempts to get all the tags.
Message Request Field
Bytes (in hex)
Description
Request Service
55
Get_Instance_Attribute_List Service (Request)
Request Path Size
03
Request Path is 3 words (6 bytes) long
Request Path
20 6B 25 00 00 00
Logical Segments: Class 0x6B, Instance 0 (starting instance)
Request Data
02 00
Number of attributes to retrieve
01 00
Attribute 1 – Symbol Name
02 00
Attribute 2 – Symbol Type
Message Reply Field
Bytes (in hex)
Description
Reply Service
D5
Get_Instance_Attribute_List Service (Reply))
Reserved
00
General Status
06
Status of 06 means: Too Much Data
Extended Status Size
00
No extended status
Reply Data
12 03 00 00
First 32-bit Instance ID
(The 1st Instance ID after the instance specified in the Request Path)
0D 00
43 69 70 52 65 61 64 44 61 74 61 31 30
16-bit Symbol Name Length
Characters in the symbol name
FF 8F
Symbol Type
51 0E 00 00
Second 32-bit Instance ID
06 00
63 6F 75 6E 74 73
16-bit Symbol Name Length
Characters in the symbol name
82 CF
Symbol Type
…
Next …
Example of retrieving the first
group of tags