Add function to step through freight codes

advtrains/trainlogic.lua

@@ -922,6 +922,16 @@ function advtrains.split_train_at_fc(train)
 	end
 end
 
+function advtrains.train_step_fc(train)
+	for i=1,#train.trainparts do
+		local w_id = train.trainparts[i]
+		local data = advtrains.wagons[w_id]
+		if data then
+			advtrains.step_fc(data)
+		end
+	end
+end
+
 function advtrains.split_train_at_index(train, index)
 	-- this function splits a train at index, creating a new train from the back part of the train.
 

advtrains/wagons.lua

@@ -874,6 +874,7 @@ function wagon.prev_fc(data)
 end
 
 function wagon.next_fc(data)
+	if not data.fc then return end
 	if data.fcrev then
 		wagon.prev_fc(data)
 		return
@@ -1127,7 +1128,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 					wagon.show_wagon_properties({id=uid}, pname)
 				end
 				if fields.fcn then
-					wagon.next_fc(data)
+					advtrains.step_fc(data)
 					wagon.show_wagon_properties({id=uid}, pname)
 				end
 			end

advtrains_luaautomation/atc_rail.lua

@@ -75,6 +75,10 @@ function r.fire_event(pos, evtdata)
 			end
 			return fc
 		end,
+		step_fc = function()
+			if not train_id then return false end
+			advtrains.train_step_fc(train)
+		end,
 		set_shunt = function()
 			if not train_id then return false end
 			train.autocouple = true