Modbus TCP Writes Fail after Reads

[merlin]

I have implemented a Separate write and read function now,  

For the most part it is working well however I do get an issue occurring a few times a day where i fail to get a read back from some random register,  almost never the same regitser. 

When this occurs it was generally forcing my script to fail as i would attempt to do a calculation on a vil value as res from  res,err mb:readregistervalue(_address, _type, _mbOrder).  will return a nil for res,  

TO try and resolve this i wrote some extra code to retry see below

Code:

function tryReadRegister(_Address, _Type, _Oder)
local _Count = 0
local _Result
repeat
   _Count = _Count + 1 
  _Result, err = mb:readregistervalue(_Address, _Type, _Oder)
      if err then
       alert("Modbus Read Error of Type "..tostring(err).."For readregistervalue at Adress "..tostring(_Address).."For Data Type "..tostring(_Type)" and Order"..tostring(_Oder).." Attempt "..tostring(_Count).." Of 3")
         sleep(0.3)
      end
until ((_Count ==3) or _Result)
if not _Result then
            alert("Modbus Read Returned no Result Forced to 0")
      return 0
   else
      return _Result
   end
end

I chose for now to return a 0 to stop the script from failing and to try ID the cause. 

I also tried to improve the situation by delaying the read attempts in between by 300ms (i assumed it possible to put delays inside functions ?

Anyway turns out when the error occurs it is not improved by trying the same again with with a delay.

But the error returned on fail is  "method called on invalid context"  I have looked this up on the forum to find this may have something to do with float32 where the solution was for a profile.  to add "Value send delta"

The script above has been modified with the message to confirm that the failure is on random register address yes, but always on a float32.   I will run it again an wait to get a result. 


But in mean time any support on what could be the issue here would be helpful.