setup modbus tcp slave

[Patrik1985]

this is the script, its updating the 3 first register mapping data but not the 2 last. if i change order in them the values works. but still change the 2 last value to 0 after the update from knx. if i deactivate and activte the script, it shows again in the modbus till the next update. 

Code:

if not mb then
 require('genohm-scada.eibdgm')
 require('luamodbus')

 -- list of coil mapping, starting from 0
 coils = { '4/1/3', '6/1/3', '5/1/3' }

 -- list of register mapping, starting from 0
 registers = { '0/1/7', '0/1/8', '6/1/4', '4/1/7', '15/1/4' }

 -- list of register data types, element count must match registers table
 regdt = { dt.int8, dt.uint16, dt.int16, dt.bool }

 -- knx group write callback
 function knxgroupwrite(event)
   local value

   -- try to find matching coil
   for id, addr in ipairs(coils) do
     if event.dst == addr then
       value = knxdatatype.decode(event.datahex, dt.bool)
       mb:setcoils(id - 1, value)
     end
   end

   -- try to find matching register
   for id, addr in ipairs(registers) do
     if event.dst == addr then
       value = knxdatatype.decode(event.datahex, regdt[ id ])
       mb:setregisters(id - 1, value)
     end
   end
 end

 -- coil write callback
 function mbwritecoils(coil, value)
   local addr = coils[ coil + 1 ]
   if addr then
     grp.write(addr, value, dt.bool)
   end
 end

 -- register write callback
 function mbwriteregisters(register, value)
   local addr = registers[ register + 1 ]
   if addr then
     grp.write(addr, value, regdt[ register + 1])
   end
 end

 -- knx group monitor, handles group writes
 knxclient = eibdgm:new({ timeout = 0.1 })
 knxclient:sethandler('groupwrite', knxgroupwrite)

 -- modbus slave, listen on all interfaces and default port 502
 mb = luamodbus.tcp()
 mb:open('0.0.0.0', 502)

 -- setting slave id is optional
 -- mb:setslave(1)

 mb:setreceivetimeout(0,1)
 mb:setmapping(#coils, 0, #registers, 0)

 -- init coils
 for id, addr in ipairs(coils) do
   value = grp.getvalue(addr)
   mb:setcoils(id - 1, value)
 end

 -- init registers
 for id, addr in ipairs(registers) do
   value = grp.getvalue(addr)
   mb:setregisters(id - 1, value)
 end

 -- set callbacks for coil and register write
 mb:setwritecoilcb(mbwritecoils)
 mb:setwriteregistercb(mbwriteregisters)
end

-- handle modbus and knx
mb:handleslave()
knxclient:step()