Rockwell Automation 284 ArmorStart User Manual - Manual (Page 256)

9-4 Explicit Messaging on DeviceNet™
• Instance:
This code identifies the specific instance within the object class
towards which the transaction is directed. The value zero is
reserved to denote that the transaction is directed towards the
class itself versus a specific instance within the class.
• Attribute:
This code identifies the specific characteristic of the object
towards which the transaction is directed. The attribute data size
is one word.
Setting up the Data File The following table lists the most common transaction types (get
information and set information), and the appropriate service, class,
instance, and attribute that corresponds to the type.
Table 9.6 Common Configuration Examples for ArmorStart
c The numeric values are in a hexadecimal format.
➁ This is the actual parameter number.
➂ The code “1” specifies the value of the instance (parameter).
Sequence of Events Use the following sequence of events as a guide for establishing
explicit messages in your SLC ladder logic.
1. Put the explicit message request data into an integer (N) file of the
SLC-500 processor.
2. Use the file copy instruction (COP) to copy the explicit message
request data entered in step 1 to the M0 File, words 224 through
256.
3. Use the examine-if-closed instruction (XIC) to monitor bit 15 of
the scanner’s module status register for an indication that it has
received a response from the ArmorStart.
4. Copy the data from the M1 file, words 224 through 256, into a file
in the SLC-500 processor using the file copy instruction (COP).
The following example shows the exact data format to perform a
“Get Attribute Single” request. This message will specifically access
parameter 104, Average Current. The first three words are shown
segmented into two bytes, corresponding to the upper and lower bytes
shown in the explicit message request table (Table 9.4).
Note: The data in the table is shown in a hexadecimal format.
Therefore parameter 104 decimal is equal to 68 hexadecimal
(0x68).
Transaction Type Service c Class c Instance c Attribute c
Get_Attribute_Single 0x0E 0x0F Par. # ➁ 1 ➂
Set_Attribute_Single 0x10 0x0F Par. # ➁ 1 ➂