Пример протокола ModBus TCP
Материал из WebHMI Wiki
Type: TCP
Default TCP port: 502
Address validation: ^(C[0-9]+)$|^(DI[0-9]+)$|^(HR[0-9]+)$|^(IR[0-9]+)$
Validation error message: Invalid register address. Valid ModBus addresses are Cxxx, DIxxx, IRxxx, HRxxx.
Code:
-- MODBUS TCP Demo Driver
function createDevices ()
addDevice({name = "C", shift = 0, base = 10, xtraFields = {1, 5}});
addDevice({name = "DI", shift = 0, base = 10, xtraFields = {2, 0}});
addDevice({name = "HR", shift = 0, base = 10, xtraFields = {3, 6, 16}});
addDevice({name = "IR", shift = 0, base = 10, xtraFields = {4, 0}});
end
local transId = 0;
local errorCount = 0;
function readRegister (reg, device, unitId)
local request = {};
-- transaction ID
transId = transId + 1;
request[1] = bit.band(bit.rshift(transId, 8), 255);
request[2] = bit.band(transId, 255);
-- protocol ID
request[3] = 0;
request[4] = 0;
-- message length
request[5] = 0;
request[6] = 6;
-- unit ID
request[7] = unitId;
-- function code
request[8] = device.xtraFields[1];
-- address of register
request[9] = bit.band(bit.rshift(reg.internalAddr, 8), 255);
request[10] = bit.band(reg.internalAddr, 255);
-- count of registers
request[11] = 0;
request[12] = 1;
if (reg.dataType == 3) then -- double word
request[12] = 2;
end
local res = sendBytes(request);
if (res == false) then
DEBUG("Can't send bytes");
return false;
end
local response = {};
-- read MBAP Header
response = readBytes(7);
if (response == false) then
DEBUG("Can't read response");
return false;
end
res = #response;
if (res ~= 7) then
errorCount = errorCount + 1;
if (errorCount > 3) then
closeConnection();
errorCount = 0;
end
DEBUG("Can't read MBAP");
return false;
end
if (response[1] ~= request[1] or response[2] ~= request[2]) then
ERROR("Wrong transaction ID. Got #" .. (response[1] * 256 + response[2]) .. " but expected #" .. (request[1] * 256 + request[2]));
return false;
end
if (response[3] ~= request[3] or response[4] ~= request[4]) then
ERROR("Wrong protocol");
return false;
end
if (response[7] ~= request[7]) then
ERROR("Wrong UnitID in response");
return false;
end
local length = response[5] * 256 + response[6];
if (length < 1) then
ERROR("Wrong length in response");
return false;
end
local responsePDU = {};
-- read MBAP Header
responsePDU = readBytes(length - 1);
if (responsePDU == false) then
DEBUG("Can't read responsePDU");
return false;
end
res = #responsePDU;
if (responsePDU[1] ~= request[8]) then
ERROR("Wrong function in response");
return false;
end
local dataLength = responsePDU[2];
if (dataLength ~= length - 3) then
ERROR("Wrong length in PDU");
return false;
end
local result = {};
if (dataLength >= 1) then
for i = 1, dataLength do
result[i] = responsePDU[2 + i];
end
end
return result;
end
function writeRegister (reg, device, unitId, newValue)
local request = {};
transId = transId + 1;
-- transaction ID
request[1] = bit.band(bit.rshift(transId, 8), 255);
request[2] = bit.band(transId, 255);
-- protocol ID
request[3] = 0;
request[4] = 0;
if (reg.dataType == 3) then -- double word
-- message length
request[5] = 0;
request[6] = 11;
-- unit ID
request[7] = unitId;
-- function code
request[8] = device.xtraFields[3];
-- address of register
request[9] = bit.band(bit.rshift(reg.internalAddr, 8), 255);
request[10] = bit.band(reg.internalAddr, 255);
-- count of registers
request[11] = 0;
request[12] = 2;
-- bytes with data
request[13] = 4;
-- value of registers
request[14] = bit.band(bit.rshift(newValue, 24), 255);
request[15] = bit.band(bit.rshift(newValue, 16), 255);
request[16] = bit.band(bit.rshift(newValue, 8), 255);
request[17] = bit.band(newValue, 255);
local res = sendBytes(request);
if (res == false) then
DEBUG("Can't send bytes");
return false;
end
local response = {};
response = readBytes(7);
if (response == false) then
DEBUG("Can't read response");
return false;
end
res = #response;
if (res ~= 7) then
DEBUG("Wrong response length");
return false;
end
if (response[1] ~= request[1] or response[2] ~= request[2]) then
ERROR("Wrong transaction ID. Got #" .. (response[1] * 256 + response[2]) .. " but expected #" .. (request[1] * 256 + request[2]));
return false;
end
if (response[3] ~= request[3] or response[4] ~= request[4]) then
ERROR("Wrong protocol");
return false;
end
if (response[7] ~= request[7]) then
ERROR("Wrong UnitID in response");
return false;
end
local length = response[5] * 256 + response[6];
if (length < 1) then
ERROR("Wrong length in response");
return false;
end
local responsePDU = {};
responsePDU = readBytes(length - 1);
if (responsePDU == false) then
DEBUG("Can't read responsePDU");
return false;
end
res = #responsePDU;
if (responsePDU[1] ~= request[8]) then
ERROR("Wrong function in response");
return false;
end
if (responsePDU[2] ~= request[9] or responsePDU[3] ~= request[10]) then
ERROR("Wrong register address in response");
return false;
end
if (responsePDU[4] ~= 0 or responsePDU[5] ~= 2) then
ERROR("Wrong register count in response");
return false;
end
else
if (device.xtraFields[2] == 0) then
ERROR("Can't write these type of registers (" .. device.name .. ")");
return false;
end
-- message length
request[5] = 0;
request[6] = 6;
-- unit ID
request[7] = unitId;
request[8] = device.xtraFields[2];
-- address of register
request[9] = bit.band(bit.rshift(reg.internalAddr, 8), 255);
request[10] = bit.band(reg.internalAddr, 255);
local val = newValue;
if (reg.dataType == 0) then
if (val > 0) then
val = 255*256;
else
val = 0;
end
end
-- value of registers
request[11] = bit.band(bit.rshift(val, 8), 255);
request[12] = bit.band(val, 255);
local res = sendBytes(request);
if (res == false) then
DEBUG("Can't send bytes");
return false;
end
local response = {};
local requestLen = #request;
response = readBytes(requestLen);
if (response == false) then
DEBUG("Can't read response");
return false;
end
res = #response;
if (res ~= requestLen) then
DEBUG("Wrong response length");
return false;
end
for i = 1,res do
if (response[i] ~= request[i]) then
DEBUG("Wrong response");
return false;
end
end
end
return true;
end