#8 base class for RTU unit sessions, handle MODBUS error responses

supervisor/session/rtu/emachine.lua

@@ -2,19 +2,21 @@ local comms = require("scada-common.comms")
 local log = require("scada-common.log")
 local types = require("scada-common.types")
 
-local txnctrl = require("supervisor.session.rtu.txnctrl")
+local unit_session = require("supervisor.session.rtu.unit_session")
 
 local emachine = {}
 
-local PROTOCOLS = comms.PROTOCOLS
 local RTU_UNIT_TYPES = comms.RTU_UNIT_TYPES
 local MODBUS_FCODE = types.MODBUS_FCODE
 
-local rtu_t = types.rtu_t
-
 local TXN_TYPES = {
-    BUILD = 0,
-    STORAGE = 1
+    BUILD = 1,
+    STORAGE = 2
+}
+
+local TXN_TAGS = {
+    "emachine.build",
+    "emachine.storage"
 }
 
 local PERIODICS = {
@@ -36,12 +38,7 @@ emachine.new = function (session_id, advert, out_queue)
     local log_tag = "session.rtu(" .. session_id .. ").emachine(" .. advert.index .. "): "
 
     local self = {
-        uid = advert.index,
-        -- reactor = advert.reactor,
-        reactor = 0,
-        out_q = out_queue,
-        transaction_controller = txnctrl.new(),
-        connected = true,
+        session = unit_session.new(log_tag, advert, out_queue, TXN_TAGS),
         has_build = false,
         periodics = {
             next_build_req = 0,
@@ -60,30 +57,20 @@ emachine.new = function (session_id, advert, out_queue)
         }
     }
 
-    ---@class unit_session
-    local public = {}
+    local public = self.session.get()
 
     -- PRIVATE FUNCTIONS --
 
-    local _send_request = function (txn_type, f_code, register_range)
-        local m_pkt = comms.modbus_packet()
-        local txn_id = self.transaction_controller.create(txn_type)
-
-        m_pkt.make(txn_id, self.uid, f_code, register_range)
-
-        self.out_q.push_packet(m_pkt)
-    end
-
     -- query the build of the device
     local _request_build = function ()
         -- read input register 1 (start = 1, count = 1)
-        _send_request(TXN_TYPES.BUILD, MODBUS_FCODE.READ_INPUT_REGS, { 1, 1 })
+        self.session.send_request(TXN_TYPES.BUILD, MODBUS_FCODE.READ_INPUT_REGS, { 1, 1 })
     end
 
     -- query the state of the energy storage
     local _request_storage = function ()
         -- read input registers 2 through 4 (start = 2, count = 3)
-        _send_request(TXN_TYPES.STORAGE, MODBUS_FCODE.READ_INPUT_REGS, { 2, 3 })
+        self.session.send_request(TXN_TYPES.STORAGE, MODBUS_FCODE.READ_INPUT_REGS, { 2, 3 })
     end
 
     -- PUBLIC FUNCTIONS --
@@ -91,49 +78,32 @@ emachine.new = function (session_id, advert, out_queue)
     -- handle a packet
     ---@param m_pkt modbus_frame
     public.handle_packet = function (m_pkt)
-        local success = false
-
-        if m_pkt.scada_frame.protocol() == PROTOCOLS.MODBUS_TCP then
-            if m_pkt.unit_id == self.uid then
-                local txn_type = self.transaction_controller.resolve(m_pkt.txn_id)
-                if txn_type == TXN_TYPES.BUILD then
-                    -- build response
-                    if m_pkt.length == 1 then
-                        self.db.build.max_energy = m_pkt.data[1]
-                    else
-                        log.debug(log_tag .. "MODBUS transaction reply length mismatch (emachine.build)")
-                    end
-                elseif txn_type == TXN_TYPES.STORAGE then
-                    -- storage response
-                    if m_pkt.length == 3 then
-                        self.db.storage.energy = m_pkt.data[1]
-                        self.db.storage.energy_need = m_pkt.data[2]
-                        self.db.storage.energy_fill = m_pkt.data[3]
-                    else
-                        log.debug(log_tag .. "MODBUS transaction reply length mismatch (emachine.storage)")
-                    end
-                elseif txn_type == nil then
-                    log.error(log_tag .. "unknown transaction reply")
-                else
-                    log.error(log_tag .. "unknown transaction type " .. txn_type)
-                end
+        local txn_type = self.session.try_resolve(m_pkt.txn_id)
+        if txn_type == false then
+            -- nothing to do
+        elseif txn_type == TXN_TYPES.BUILD then
+            -- build response
+            if m_pkt.length == 1 then
+                self.db.build.max_energy = m_pkt.data[1]
             else
-                log.error(log_tag .. "wrong unit ID: " .. m_pkt.unit_id, true)
+                log.debug(log_tag .. "MODBUS transaction reply length mismatch (emachine.build)")
             end
+        elseif txn_type == TXN_TYPES.STORAGE then
+            -- storage response
+            if m_pkt.length == 3 then
+                self.db.storage.energy = m_pkt.data[1]
+                self.db.storage.energy_need = m_pkt.data[2]
+                self.db.storage.energy_fill = m_pkt.data[3]
+            else
+                log.debug(log_tag .. "MODBUS transaction reply length mismatch (emachine.storage)")
+            end
+        elseif txn_type == nil then
+            log.error(log_tag .. "unknown transaction reply")
         else
-            log.error(log_tag .. "illegal packet type " .. m_pkt.scada_frame.protocol(), true)
+            log.error(log_tag .. "unknown transaction type " .. txn_type)
         end
-
-        return success
     end
 
-    public.get_uid = function () return self.uid end
-    public.get_reactor = function () return self.reactor end
-    public.get_db = function () return self.db end
-
-    public.close = function () self.connected = false end
-    public.is_connected = function () return self.connected end
-
     -- update this runner
     ---@param time_now integer milliseconds
     public.update = function (time_now)
@@ -148,6 +118,9 @@ emachine.new = function (session_id, advert, out_queue)
         end
     end
 
+    -- get the unit session database
+    public.get_db = function () return self.db end
+
     return public
 end