Devicenet Explicit Messages; Basic Format Of Explicit Messages - Omron DEVICENET SAFETY - 04-2005 Operation Manual

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DeviceNet Explicit Messages

DeviceNet explicit messages sent from the Master Unit to the DST1-series Safety I/O Terminals can be used
to read or write any parameter of a specified DST1-series Safety I/O Terminals. The DST1-series Safety I/O
Terminals processes the commands sent from the master and then returns responses.
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Basic Format of Explicit Messages

The basic format of each command and response is shown below.
Command Block
Destination node
address
Destination Node Address
The node address of the Unit that is sending the explicit message is specified with on hexadecimal byte.
Service Code, Class ID, Instance ID, and Attribute ID
The parameters used for specifying the command, processing object, and processing content.
Note: The number of bytes designated for the class ID, instance ID, and attribute ID depend on the Master
Unit. When sent from an OMRON DeviceNet Master, the class ID and instance ID are 2 bytes (4 dig-
its) each, and the attribute ID is 1 byte (2 digits).
Data
Data is not required when a read command is used.
Response Block
Normal Response Block
Number of bytes received
Error Response Block
Number of bytes received
0004 hex (fixed)
Number of Bytes Received
The number of bytes received from the source node address is returned in hexadecimal. When an error re-
sponse is returned for an explicit message, the number of bytes is always 0004 hex.
Source Node Address
The node address of the node from which the command was sent is returned in hexadecimal.
Service Code
For normal completions, the service code specified in the command with the leftmost bit turned ON is stored
as shown in the following table.
Function
Read data
Write data
Reset
Save
When an error response is returned for an explicit message, the value is always 94 hex.
Data
Read data is included only when a read command is executed.
Error Code
The explicit message error code. For details, refer to the list of error codes in the following table.
A-1 Basic Format of Explicit Messages
Service Class
code ID
Source node address
Source node address
Command service code
10 hex
0E hex
05 hex
16 hex
Instance Attribute
ID ID
Service code
Service code
Response service code
90 hex
8E hex
85 hex
96 hex
Data
Data
Error code
89