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ControlLogix 7252 LDT Interface Manual
Revision 1.5
Chapter 4: Message Instructions
The programming of the 7252 module’s Setup data requires the use of Message Instructions. The format of this
instruction is shown below.
1.
A different message instruction is needed for each channel of the 7252 module.
2.
The message instruction sends data to or reads data from the 7252 module only when the rung transitions from
false to true.
3.
The Message Control tag, message_ch1 in this example, used for Message Instruction Control must have the
MESSAGE data type.
4.
Clicking on the button in the Message Instruction opens the Message Configuration Window, shown below. Enter
the appropriate data for the channel and operation being performed. When finished, click on the Apply button to
accept the new data.
Message Type: CIP Generic
Service Type: Must be Custom
Service Code: 4C to write data to the 7252 module, 4B to read data from the 7252 module
Class: Must be equal to 4.
Instance: Determined by the type of data being transferred, see the table below.
Attribute: Must be set to zero.
Source Element: If the Message Instruction is being used to send data to the 7252 module, then the source parameter
will be the first tag of the array that contains the data to be sent to the 7252 module.
If the Message Instruction is being used to read data from the 7252 module, than the source parameter
must be left blank.
