Omron EJ1 - 07-2008, Operation Manual

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Overview of Explicit Message Communications Section 6-1
6-1-2 Explicit Messages Types
The explicit messages sent to the DeviceNet Communications Unit can be
divided into two types, as follows:
Sending CompoWay/F Communications Commands to Temperature Controllers
The master can send CompoWay/F communications commands to the Tem-
perature Controllers by sending to the DeviceNet Communications Unit as
explicit messages data.
The DeviceNet Communications Unit automatically converts the explicit mes-
sages to CompoWay/F communications commands and sends them to the
Temperature Controllers. The responses from the Temperature Controllers
are converted into explicit messages and returned to the master. Compo-
Way/F commands are used to read from and write to the Temperature Con-
troller variable area and to execute operation commands.
CompoWay/F commands consist of binary commands and ASCII commands.
CompoWay/F Binary
Commands CompoWay/F binary commands are CompoWay/F communications com-
mands expressed in hexadecimal, and are easy to execute from ladder pro-
grams. CompoWay/F communications commands that include ASCII data,
however, cannot be sent or received. Therefore, Read Controller Attribute (05
03) and broadcasting (communications unit number = XX) cannot be used.
CompoWay/F ASCII
Commands CompoWay/F ASCII commands are CompoWay/F communications com-
mands expressed in ASCII, so numerical values must be converted to ASCII
when executing these commands from a ladder program. All CompoWay/F
communications commands can be sent and received, including Read Con-
troller Attribute (05 03) and broadcasting (unit number = XX), which cannot be
used with CompoWay/F binary commands.
Sending Explicit Messages to the DeviceNet Communications Unit
The master can send explicit messages to the DeviceNet Communications
Unit to control various operations supported by the DeviceNet Communica-
tions Unit and to read settings and status information.
Explicit messages are used to read and write various maintenance data for
the DeviceNet Communications Unit and Temperature Controllers.
6-1-3 Explicit Messages Basic Format
The basic format of explicit message commands and responses is as follows:
Command Block
Destination Node Address This parameter specifies the node address of the DeviceNet Communications
Unit to which the explicit messages (commands) will be sent in single-byte (2-
digit) hexadecimal.
Service Code, Class ID,
Instance ID, Attribute ID These parameters specify the command type, processing target, and pro-
cessing details.
When sending explicit messages to the DeviceNet Communications Unit,
specify the target Temperature Controller in the Instance ID. (Specify the Tem-
perature Controller's communications unit number and channel number).
The Attribute ID does not need to be specified for some commands.
Destina-
tion node
address
Service
code
Class ID
Instance
ID
Attribute
ID
Data