Require matching UID

rmodbus · Jul 24, 2015 · 838c900 · 838c900
1 parent eb6c7b9
commit 838c900
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Showing 2 changed files with 24 additions and 15 deletions.
diff --git a/lib/rmodbus/tcp_server.rb b/lib/rmodbus/tcp_server.rb
@@ -49,15 +49,19 @@ def serve(io)
         proto_id = header[2,2]
         len = header[4,2].unpack('n')[0]
         unit_id = header.getbyte(6)
-				if proto_id == "\x00\x00" or unit_id == @uid
+				if proto_id == "\x00\x00"
           req = io.read(len - 1)
-          log "Server RX (#{req.size} bytes): #{logging_bytes(req)}"
+				  if unit_id == @uid || unit_id == 0
+            log "Server RX (#{req.size} bytes): #{logging_bytes(req)}"
 
-          pdu = exec_req(req, @coils, @discrete_inputs, @holding_registers, @input_registers)
+            pdu = exec_req(req, @coils, @discrete_inputs, @holding_registers, @input_registers)
 
-          resp = tx_id + "\0\0" + (pdu.size + 1).to_word + @uid.chr + pdu
-          log "Server TX (#{resp.size} bytes): #{logging_bytes(resp)}"
-          io.write resp
+            resp = tx_id + "\0\0" + (pdu.size + 1).to_word + @uid.chr + pdu
+            log "Server TX (#{resp.size} bytes): #{logging_bytes(resp)}"
+            io.write resp
+          else
+            log "Ignored server RX (invalid unit ID #{unit_id}, #{req.size} bytes): #{logging_bytes(req)}"
+          end
         end
 			end
 		end

diff --git a/spec/tcp_server_spec.rb b/spec/tcp_server_spec.rb
@@ -3,23 +3,28 @@
 
 describe ModBus::TCPServer do
   before :all do
-    @server = ModBus::TCPServer.new(8502,1)
+    unit_ids = (1..247).to_a.shuffle
+    valid_unit_id = unit_ids.first
+    @invalid_unit_id = unit_ids.last
+    @server = ModBus::TCPServer.new(8502, valid_unit_id)
     @server.coils = [1,0,1,1]
     @server.discrete_inputs = [1,1,0,0]
     @server.holding_registers = [1,2,3,4]
     @server.input_registers = [1,2,3,4]
     @server.start
     @cl = ModBus::TCPClient.new('127.0.0.1', 8502)
-    @slave = @cl.with_slave(1)
-    @slave.read_retries = 1
+    @cl.read_retries = 1
+    @slave = @cl.with_slave(valid_unit_id)
   end
 
-  it "should silent if UID has mismatched" do
-    @cl.with_slave(2).read_coils(1,3)
-    #lambda { @cl.with_slave(2).read_coils(1,3) }.should raise_exception(
-    #  ModBus::Errors::ModBusException,
-    #  "Server did not respond"
-    #)
+  it "should succeed if UID is broadcast" do
+    @cl.with_slave(0).read_coils(1,3)
+  end
+
+  it "should fail if UID is mismatched" do
+    lambda { @cl.with_slave(@invalid_unit_id).read_coils(1,3) }.should raise_exception(
+      ModBus::Errors::ModBusTimeout
+    )
   end
 
   it "should send exception if function not supported" do