Modbus Float32

[sjfp]

Hi all need some with a float32 issue. 
When using Modbus profiles like: 
{
"product_code": "Socket Meter",
  "mapping": [
{"name": " Active Power", "bus_datatype": "float32", "datatype": "float32","units": "kWh", "type": "inputregister", "address": 52},
{"name": "Total System", "bus_datatype": "float32", "datatype": "float32","units": "kW", "type": "inputregister", "address": 72}],
  "manufacturer": "Eastron",
  "name": "1Phase Smart Meter",
  "product_range": "SDM-M",
  "description": "Modbus 3 Phase Meter Direct Connect"
}


Works fine and we get the correct values.

But we need to use modbus scripting rather than profiles, so using:

require('luamodbus')
mb = luamodbus.rtu()
mb:open('/dev/RS485-1', 9600, 'N', 8, 1, 'H')
res, err = mb:connect()
if res then
  mbetslave(1)
  value1 = mb:readregistervalue(52,"float32","n")  --Meter (n=no swap, w=word swap, b=byte swap, bw=byte and word swap)   
  value2 = mb:readregistervalue(72,"float32","n")
log('V1: ' .. value1 .. ' and V2: '..value2)
else
  log('Umm !!, connection failed : '.. err)
end
mb:close()


But not getting any figures (0 only), So I am assuming there must be a conversion problem with bus data type, I need to do as well.
Any suggestion's would be appreciated.