Rockwell Automation 1203-SM1 SLC to SCANport Communication Module - Manual (Page 42)

4–14 Using Enhanced Mode
Publication 1203–5.9 –– October 1996
Figure 4.11 shows the first M0 message buffer structure.
Figure 4.11
SLC to SCANport Module M0 Buffer 0 Message Structure
Service
Class
Instance
Attribute
Request Length = n
Req Data 2
Req Data n
Req Data 1
...
M0:e.b00
M0:e.b01
M0:e.b02
M0:e.b03
M0:e.b04
M0:e.b05
M0:e.bxx
e = slot location
b = buffer 0–7
Header
Information
Where:
This field: Specifies:
Service
The action or service requested. The following service values are
available:
Enter this value: To request this service:
0001H (1 decimal) Read Parameter Full/All Info
0005H (5 decimal) Reset to Default
➀
000eH (14 decimal) Get Attribute Single
0010H (16 decimal) Set Attribute Single
0015H (21 decimal) Restore from Storage
➀
0016H (22 decimal) Save to Storage
➀
0032H (50 decimal) Get Attribute Scattered
0034H (52 decimal) Set Attribute Scattered
004bH (75 decimal) Read Enum String
➀
➀
Not all SCANport devices support these services.
For example, if you enter a service value of 0001H (1 decimal), you
are requesting that the SCANport device provide all available
information about a particular object. A service value of 000eH is a
request for only one piece of information about a particular object.
Class
The type of object to access within the SCANport device. The class
is the first index into the SCANport device’s database. It directs the
message to the desired functional database. For example, a class
value of 000fH (15 decimal) indicates that the message is intended to
access the parameter database.
Instance
A particular occurrence of an object in the SCANport device. The
instance provides an index into the referenced functional database.
For example, when accessing the parameter database, the instance
value is the parameter number. If you want to access information
about all instances of the object, specify an instance of 0.
Attribute
A specific piece of information about an object. Values are always
less than 256. For example, in a parameter object, an attribute value
of 0001H (1 decimal) indicates that the message is accessing the
parameter value. An attribute value of 0007H (7 decimal) indicates
that the message is accessing the parameter name text string.
Request
length
The length, in bytes, in this request. This value is normally less than
or equal to 96 bytes. However, Get/Set Attribute Scattered messages
can be longer.