How to retrieve simple udp packets those have only length/data?

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I'm trying to receive simple udp packet with length and data.
Packet structure has no header/trailer and like followings.
|LENGTH(2byte)|DATA(variable length)|
ex)
0C 00 00 01 02 03 04 05 06 07 08 09 0a 0b

I defined in the protocol like followings but didn't work.
The packets can be seen in stream viewer but not handled in the connector.

[Parameter]

<Param id="100">
<Name>DataLength</Name>
<Type>length</Type>
<Interprete>
<RawType>numeric text</RawType>
<LengthType>fixed</LengthType>
<Length>2</Length>
<Type>double</Type>
</Interprete>
<Length>
<Content>
<Param>1</Param>
</Content>
</Length>
</Param>

<Param id="101">
<Name>DataBody</Name>
<Type>read</Type>
<Interprete>
<RawType>other</RawType>
<Type>string</Type>
<LengthType>next param</LengthType>
</Interprete>
</Param>

[Response]

<Response id="100">
<Name>DevicePacket</Name>
<Content>
<Param>100</Param>
<Param>101</Param>
</Content>
</Response>

[Trigger]

<Trigger id="100">
<Name>Before Packet</Name>
<On id="100">response</On>
<Time>before</Time>
<Type>action</Type>
<Content>
<Id>10</Id>
<Id>11</Id>
</Content>
</Trigger>

<Trigger id="101">
<Name>After Packet</Name>
<On id="100">response</On>
<Time>after</Time>
<Type>action</Type>
<Content>
<Id>100</Id>
</Content>
</Trigger>

[Action]

<Action id="10">
<Name>Response Read</Name>
<On>response</On>
<Type>read</Type>
</Action>
<Action id="11">
<Name>Response Length</Name>
<On>response</On>
<Type>length</Type>
</Action>

Something wrong or missing?

Hideyuki Imaida [DevOps Advocate] Selected answer as best 5th June 2024
Hideyuki Imaida [DevOps Advocate] commented

I tried replacing the order between action:read and action:length and the packet received correctly. (action:length > action:read)
Are these reasonable?
In doc – https://docs.dataminer.services/develop/devguide/Connector/ConnectionsSerialCreatingCommandsAndResponses.html#responses-with-length-field

It said “Note that the length action needs to be after “read response”.”…
Marieke Goethals [SLC] [DevOps Catalyst] commented

Hi,
I noticed that this question has been open for some time now. If this has been resolved in the meantime, could you select the best answer so the question is closed? If none of the answers provided the solution, but you have found it yourself, could you add an answer of your own?

4 Answers

1
7.94K 1 Comment

Hi Hideyuki,

Could you please try again using the following parameter definition? The 'length' action should also not be needed anymore.

<Param id="100">
<Name>DataLength</Name>
<Type>length</Type>
<Interprete>
<RawType>numeric text</RawType>
<LengthType>fixed</LengthType>
<Length>2</Length>
<Type>double</Type>
<Base>16</Base>
</Interprete>
</Param>

<Param id="101">
<Name>DataBody</Name>
<Type>read</Type>
<Interprete>
<RawType>other</RawType>
<Type>string</Type>
<LengthType id="100">other param</LengthType>
</Interprete>
</Param>

Hideyuki Imaida [DevOps Advocate] Posted new comment 21st February 2024
Hideyuki Imaida [DevOps Advocate] commented

Hi Tom,

Thank you for the reply.
I’ve already tried these definition but didn’t work.
I think this is what explained in the doc.
https://docs.dataminer.services/develop/devguide/Connector/ConnectionsSerialCreatingCommandsAndResponses.html#responses-with-dynamically-defined-length

I tried param type of 100 as both ‘length’ and ‘read’ but didn’t work.
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