diff --git a/mesecons_fpga/init.lua b/mesecons_fpga/init.lua
index 1b9c49e..5623838 100644
--- a/mesecons_fpga/init.lua
+++ b/mesecons_fpga/init.lua
@@ -116,42 +116,45 @@ plg.register_nodes({
 	after_dig_node = function(pos, node)
 		mesecon.receptor_off(pos, plg.rules[node.name])
 	end,
-	on_rotate = minetest.global_exists("screwdriver") and function(pos, node, user, mode)
+	on_rotate = function(pos, node, user, mode)
 		local abcd1 = {"A", "B", "C", "D"}
 		local abcd2 = {A = 1, B = 2, C = 3, D = 4}
+		local ops = {"op1", "op2", "dst"}
 		local dir = 0
 		if mode == screwdriver.ROTATE_FACE then -- clock-wise
 			dir = 1
 			if user and user:is_player() then
 				minetest.chat_send_player(user:get_player_name(),
-						"FPGA has been rotated clock-wise.")
+						"FPGA ports have been rotated clock-wise.")
 			end
 		elseif mode == screwdriver.ROTATE_AXIS then -- counter-clock-wise
 			dir = -1
 			if user and user:is_player() then
 				minetest.chat_send_player(user:get_player_name(),
-						"FPGA has been rotated counter-clock-wise.")
+						"FPGA ports have been rotated counter-clock-wise.")
 			end
 		end
 		local meta = minetest.get_meta(pos)
-		local instr = meta:get_string("instr")
-		local out = ""
+		local instr = lcore.deserialize(meta:get_string("instr"))
 		for i = 1, #instr do
-			local char = instr:sub(i, i)
-			local num = abcd2[char]
-			if num then
-				num = num + dir
-				if num > 4 then
-					num = 1
-				elseif num < 1 then
-					num = 4
+			for k = 1, #ops do
+				local op = ops[k]
+				local o = instr[i][op]
+				if o and o.type == "io" then
+					local num = abcd2[o.port]
+					num = num + dir
+					if num > 4 then
+						num = 1
+					elseif num < 1 then
+						num = 4
+					end
+					instr[i][op].port = abcd1[num]
 				end
-				char = abcd1[num]
 			end
-			out = out..char
 		end
-		meta:set_string("instr", out)
-		plg.update_formspec(pos, out)
+		local is = lcore.serialize(instr)
+		meta:set_string("instr", is)
+		plg.update_formspec(pos, is)
 	end,
 })