Rockwell Automation Logix5000 Controllers Messages Programming Manual - Manual (Page 14)

Chapter 1 Controller messages
To determine or change the number of unconnected buffers, use a MSG
instruction.
• The range is 10 to 40 unconnected buffers.
• The default number is 10.
• Each unconnected buffers uses 1.1 KB of memory.
Get the number of unconnected buffers
To determine the number of unconnected buffers that are currently available,
configure a Message (MSG) instruction as follows.
On this tab For this item Type or choose
Configuration Message Type CIP Generic
Service Type Custom
Service Code 3
Class 304
Instance 1
Attribute 0
Source Element source_array where data type = SINT[4]
In this element Enter
source_array[0]
1
source_array[1]
0
source_array[2] 17
source_array[3]
0
Source Length (bytes) 4 (Write 4 SINTs.)
Destination Element destination_array where data type = SINT[10] (Leave all values = 0.)
destination_array[6] = current number of unconnected buffers
Communication Path 1, slot_number_of_controller
Get or set the number of
unconnected buffers
14 Rockwell Automation Publication 1756-PM012F-EN-P - October 2014