NDC BETA LaserMike LaserSpeed Pro 8500-4, Instruction Handbook Manual

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LaserSpeed Pro 8500-4 Instruction Handbook:
Profibus DP™
11-5
The command code is used to request a particular PKW service. The available PKW command codes are
detailed later in this document.
The command code qualifier is used to carry additional information relating to the command. This includes
enumeration indices, database item identifiers, string segments, etc.
The command data is used by the master to send long, float or string information. The gauge uses the com-
mand data to provide enumeration, limit, value, and string data as appropriate according to the command
code.
11.3.1 Detection of Matching PKW Response
After a master has initiated a PKW command by setting the PKW request header appropriately, it must wait
for a matching response from the LaserSpeed Pro gauge.
A matching response is detected by comparing the command code, and command qualifier within the PKW
response header to those issued in the PKW request header. Since the toggle bit is always reflected by the
gauge, it is also possible to include the toggle bit in the comparison.
The gauge will always respond with command code, and command qualifier, even if the request is not valid.
The response code should be checked before any use is made of the response data. A non-zero response
code indicates that the request failed.
Currently, the gauge responds with a success response code and data of all zeroes for unrecognized com-
mand codes.
Response Code Description
0 Success – The command has been successfully processed.
1 Error – The command referenced an unknown item
2
Error – The command referenced an item of the incorrect
type
3
Error – A request to save a string cannot be performed be-
cause no string data has previously been provided
4 Error – RESERVED.
5 Error – Attempted write to read-only item