The Message Element - Allen-Bradley MicroLogix 1400 Instruction Manual

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The Message Element

Message File Elements
Sub- Name Description
Element
0 to 1 Reserved
2 Messaging Type: 0 (for PCCC), 1 (for CIP), 2 (for Modbus Master)
3 for PCCC Messaging: bits 07-00 (CMD code), bits 15-08 (FNC code)
for CIP: bits 07-00 (Service Code), bits 15-08 (Supplemental Object
Path Data Count)
for Modbus Master: bits 07-00 (Function Code), bits 15-08 (Reserved)
4 Internal Physical Address
5 MG11:0.RBL PCCC: Remote Bridge Link ID
Modbus Master: not used
6 MG11:0.LBN PCCC: Local Bridge Node Address
Modbus Master: not used
7 MG11:0.RBN PCCC: Remote Bridge Node Address
Modbus Master: not used
8 MG11:0.CHN Channel: bits 07-00 (0 for Channel 0,1 for Channel 1)
Slot: bits 15-08 (Not used)
9 MG11:0.NOD Target Node Number
10 MG11:0.MTO Message timeout setting or preset in seconds
11 PCCC: Number of bytes to read/write
Modbus Master: Number of Modbus elements to read/write
The MSG instruction built into the controller uses a MG data file to
process the message instruction. The MG data file, shown at left, is
accessed using the MG prefix. Each message instruction utilizes an
element within a MG data file. For example, MG11:0 is the first element in
message data file 11.
Message File Sub-Elements
Each MSG instruction must use a unique Element in a MSG File. The MSG
element for each MSG instruction holds all of the parameters and status
information for that particular MSG instruction.
Each MSG File Element consists of Sub-Elements 0...24 as shown in the
following table.
Communications Instructions
Paramet Size User Program
er
Access
Word read only
Word read only
derived Word read only
Word read only
Y Word read only
Y Word read only
Y Word read only
Y Word read/write
Y Word read/write
Y Word read/write
Word read only
Publication 1766-RM001A-EN-P - October 2008
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