#338 resolved diagnostic warnings

supervisor/session/rtu/txnctrl.lua

@@ -55,7 +55,7 @@ function txnctrl.new()
     -- mark a transaction as resolved to get its transaction type
     ---@nodiscard
     ---@param txn_id integer
-    ---@return integer txn_type
+    ---@return integer|nil txn_type
     function public.resolve(txn_id)
         local txn_type = nil
 

supervisor/session/rtu/unit_session.lua

@@ -73,7 +73,13 @@ function unit_session.new(session_id, unit_id, advert, out_queue, log_tag, txn_t
         if m_pkt.scada_frame.protocol() == PROTOCOL.MODBUS_TCP then
             if m_pkt.unit_id == unit_id then
                 local txn_type = self.transaction_controller.resolve(m_pkt.txn_id)
-                local txn_tag = " (" .. util.strval(txn_tags[txn_type]) ..  ")"
+                local txn_tag = util.c(" (", txn_tags[txn_type], ")")
+
+                if txn_type == nil then
+                    -- couldn't find this transaction
+                    log.debug(log_tag .. "MODBUS: expired or spurious transaction reply (txn_id " .. m_pkt.txn_id .. ")")
+                    return false, m_pkt.txn_id
+                end
 
                 if bit.band(m_pkt.func_code, MODBUS_FCODE.ERROR_FLAG) ~= 0 then
                     -- transaction incomplete or failed

supervisor/startup.lua

@@ -21,7 +21,7 @@ local supervisor = require("supervisor.supervisor")
 
 local svsessions = require("supervisor.session.svsessions")
 
-local SUPERVISOR_VERSION = "v1.0.3"
+local SUPERVISOR_VERSION = "v1.0.4"
 
 local println = util.println
 local println_ts = util.println_ts