#8 base class for RTU unit sessions, handle MODBUS error responses
This commit is contained in:
Mikayla Fischler
132
supervisor/session/rtu/unit_session.lua
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132
supervisor/session/rtu/unit_session.lua
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local comms = require("scada-common.comms")
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local log = require("scada-common.log")
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local types = require("scada-common.types")
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local txnctrl = require("supervisor.session.rtu.txnctrl")
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local unit_session = {}
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local PROTOCOLS = comms.PROTOCOLS
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local MODBUS_FCODE = types.MODBUS_FCODE
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local MODBUS_EXCODE = types.MODBUS_EXCODE
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-- create a new unit session runner
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---@param log_tag string
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---@param advert rtu_advertisement
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---@param out_queue mqueue
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---@param txn_tags table
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unit_session.new = function (log_tag, advert, out_queue, txn_tags)
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local self = {
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log_tag = log_tag,
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txn_tags = txn_tags,
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uid = advert.index,
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reactor = advert.reactor,
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out_q = out_queue,
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transaction_controller = txnctrl.new(),
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connected = true,
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device_fail = false
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}
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---@class _unit_session
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local protected = {}
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---@class unit_session
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local public = {}
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-- PROTECTED FUNCTIONS --
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-- send a MODBUS message, creating a transaction in the process
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---@param txn_type integer transaction type
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---@param f_code MODBUS_FCODE function code
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---@param register_param table register range or register and values
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protected.send_request = function (txn_type, f_code, register_param)
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local m_pkt = comms.modbus_packet()
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local txn_id = self.transaction_controller.create(txn_type)
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m_pkt.make(txn_id, self.uid, f_code, register_param)
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self.out_q.push_packet(m_pkt)
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end
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-- try to resolve a MODBUS transaction
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---@param m_pkt modbus_frame MODBUS packet
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---@return integer|false txn_type transaction type or false on error/busy
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protected.try_resolve = function (m_pkt)
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if m_pkt.scada_frame.protocol() == PROTOCOLS.MODBUS_TCP then
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if m_pkt.unit_id == self.uid then
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local txn_type = self.transaction_controller.resolve(m_pkt.txn_id)
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local txn_tag = " (" .. self.txn_tags[txn_type] .. ")"
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if bit.band(m_pkt.func_code, MODBUS_FCODE.ERROR_FLAG) ~= 0 then
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-- transaction incomplete or failed
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local ex = m_pkt.data[1]
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if ex == MODBUS_EXCODE.ILLEGAL_FUNCTION then
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log.error(log_tag .. "MODBUS: illegal function" .. txn_tag)
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elseif ex == MODBUS_EXCODE.ILLEGAL_DATA_ADDR then
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log.error(log_tag .. "MODBUS: illegal data address" .. txn_tag)
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elseif ex == MODBUS_EXCODE.SERVER_DEVICE_FAIL then
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if self.device_fail then
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log.debug(log_tag .. "MODBUS: repeated device failure" .. txn_tag)
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else
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self.device_fail = true
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log.warning(log_tag .. "MODBUS: device failure" .. txn_tag)
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end
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elseif ex == MODBUS_EXCODE.ACKNOWLEDGE then
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-- will have to wait on reply, renew the transaction
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self.transaction_controller.renew(m_pkt.txn_id, txn_type)
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elseif ex == MODBUS_EXCODE.SERVER_DEVICE_BUSY then
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-- will have to wait on reply, renew the transaction
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self.transaction_controller.renew(m_pkt.txn_id, txn_type)
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log.debug(log_tag .. "MODBUS: device busy" .. txn_tag)
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elseif ex == MODBUS_EXCODE.NEG_ACKNOWLEDGE then
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-- general failure
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log.error(log_tag .. "MODBUS: negative acknowledge (bad request)" .. txn_tag)
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elseif ex == MODBUS_EXCODE.GATEWAY_PATH_UNAVAILABLE then
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-- RTU gateway has no known unit with the given ID
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log.error(log_tag .. "MODBUS: gateway path unavailable (unknown unit)" .. txn_tag)
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elseif ex ~= nil then
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-- unsupported exception code
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log.debug(log_tag .. "MODBUS: unsupported error " .. ex .. txn_tag)
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else
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-- nil exception code
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log.debug(log_tag .. "MODBUS: nil exception code" .. txn_tag)
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end
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else
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-- clear device fail flag
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self.device_fail = false
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-- no error, return the transaction type
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return txn_type
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end
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else
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log.error(log_tag .. "wrong unit ID: " .. m_pkt.unit_id, true)
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end
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else
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log.error(log_tag .. "illegal packet type " .. m_pkt.scada_frame.protocol(), true)
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end
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-- error or transaction in progress, return false
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return false
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end
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-- get the public interface
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protected.get = function () return public end
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-- PUBLIC FUNCTIONS --
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-- get the unit ID
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public.get_uid = function () return self.uid end
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-- get the reactor ID
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public.get_reactor = function () return self.reactor end
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-- close this unit
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public.close = function () self.connected = false end
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-- check if this unit is connected
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public.is_connected = function () return self.connected end
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-- check if this unit is faulted
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public.is_faulted = function () return self.device_fail end
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return protected
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end
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return unit_session
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