| Issue 48: | short and ushort with Modbus RTU | |
| 1 person starred this issue and may be notified of changes. | Back to list |
I am using a Trio Motion controller, connected via USB for programing and with serial / Modbus for data transfer to run a custom application. What steps will reproduce the problem? 1. try to write 38000 in a register "master.WriteSingleRegister(slaveID, vrID, value);" What is the expected output? What do you see instead? In the controller, the written value is -27536.0, it should be 38000. What version of the product are you using? On what operating system? - Windows XP SP3, with version 3.5 installed - My program in in C# in Visual Studio 2005 - Modbus.dll 1.11.0.0 - log4net.dll v1.2.10.0 Please provide any additional information below On the trace I am doing, up to the "master.WriteSingleRegister(slaveID, vrID, value);", the value is in a ushort variable. I will have to install Visual Studio 2008 to try debugging in the Modbus.dll. Cheers !!! |
|
,
Jun 18, 2009
I don't see how this could be an NModbus issue. How are you reading the value back from your device? My guess is you're using the wrong numbering format... the register value is assumed to be an unsigned integer. |
|
,
Jun 30, 2009
Hi, When I read back the value from the nmodbus library, the value is the same (38000) so the library is consistent. After doing some more research, I realized that my controller registers were in 32 bit floating point (signed). The old way I was used to connect to it used Modicon Modbus protocol (enabling floating point data transfer) So if i understood well, using the nmodbus library I cant write in the memory of my the controller a true signed 16 bit Integer. Because once the packed is recieved by my controller it will convert the value to a signed short. One solution to this is to convert the value back (in the controller) to a unsigned. I didnt open the library yet in .NET 2008. Do you think is is feasable to modify the library to accept different numbering format? Thanks a lot and very nice work with this library, It helped me a lot realizing my project. |
|
 Sign in to add a comment
|
