Omron CP - PROGRAMMING MANUAL 05-2007 - Page 892

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Network Instructions Section 3-24
3-24-2 About Explicit Message Instructions (CP1H Only)
Methods for Using Explicit
Message Communications
There are two methods that can be used to send explicit messages from a
PLC.
• Use the CMND(490) to send a FINS command code of 2801 hex
(EXPLICIT MESSAGE SEND).
• Use the following Explicit Message Instructions.
Explicit Message
Instructions
The following instructions are called Explicit Message Instructions.
Features of Explicit
Message Instructions
• Explicit Message Instructions do not require giving a 2801 hex FINS com-
mand and are much simpler to program than CMND(490).
• With the EXPLICIT GET/SET ATTRIBUTE instructions, entering the ser-
vice code is not required and only information from the class ID onward
needs to be entered.
• With the EXPLICIT WORD READ/WRITE instructions, the I/O memory
address in the local and remote CPU Units can be specified directly.
Code specifications for area types and hexadecimal word addresses are
not required. (These are required for CMND(490) instructions with service
code 1E (word data read) or 1F hex (word data write).)
This enables easy reading and writing of data between CPU Units using
explicit message communications (like SEND/RECV instructions for FINS
commands).
Cycle time (First cycle)
END(001) executed.
3. Processing is
divided up over
several cycles.
Cycle time (Second cycle)
Program execution Program execution
1. SEND(090),
RECV(098), or
CMND(490)
END(001) executed.
I/O refreshing
Peripheral
servicing
Peripheral
servicing
Sends command.
Receives
response.
2. Communications processing
during “serial communications
port servicing” (Composes and
sends FINS command.)
4. Communications processing
during “serial communications
port servicing” (Receives
response.)
I/O refreshing
Instruction Name Outline
EXPLT(720) EXPLICIT MES-
SAGE SEND
Sends an explicit message with any service
code. Note: Functionally, this instruction is the
same as sending CMND(490) with a FINS com-
mand code of 2801 hex.
EGATR(721) EXPLICIT GET
ATT RIBU TE
Sends an explicit message with a service code
of 0E hex (GET ATTRIBUTE SINGLE).
ESATR(721) EXPLICIT SET
ATT RIBU TE
Sends an explicit message with a service code
of 10 hex (SET ATTRIBUTE SINGLE).
EGATR(721) EXPLICIT WORD
READ
Uses an explicit message to read data from a
CPU Unit.
EGATR(721) EXPLICIT WORD
WRITE
Uses an explicit message to write data to a
CPU Unit.