first init

rtu_transport_test.go

@@ -0,0 +1,189 @@
+package modbus
+
+import (
+	"testing"
+	"io"
+	"net"
+	"time"
+)
+
+func TestAssembleRTUFrame(t *testing.T) {
+	var rt		*rtuTransport
+	var frame	[]byte
+
+	rt		= &rtuTransport{}
+
+	frame		= rt.assembleRTUFrame(&pdu{
+		unitId:		0x33,
+		functionCode:	0x11,
+		payload:	[]byte{0x22, 0x33, 0x44, 0x55},
+	})
+	// expect 1 byte of unit id, 1 byte of function code, 4 bytes of payload and
+	// 2 bytes of CRC
+	if len(frame) != 8 {
+		t.Errorf("expected 8 bytes, got %v", len(frame))
+	}
+	for i, b := range []byte{
+		0x33, 0x11, // unit id and function code
+		0x22, 0x33, // payload
+		0x44, 0x55, // payload
+		0xf0, 0x93, // CRC
+	} {
+		if frame[i] != b {
+			t.Errorf("expected 0x%02x at position %v, got 0x%02x", b, i, frame[i])
+		}
+	}
+
+	frame		= rt.assembleRTUFrame(&pdu{
+		unitId:		0x31,
+		functionCode:	0x06,
+		payload:	[]byte{0x12, 0x34},
+	})
+	// expect 1 byte of unit if, 1 byte of function code, 2 bytes of payload and
+	// 2 bytes of CRC
+	if len(frame) != 6 {
+		t.Errorf("expected 6 bytes, got %v", len(frame))
+	}
+	for i, b := range []byte{
+		0x31, 0x06, // unit id and function code
+		0x12, 0x34, // payload
+		0xe3, 0xae, // CRC
+	} {
+		if frame[i] != b {
+			t.Errorf("expected 0x%02x at position %v, got 0x%02x", b, i, frame[i])
+		}
+	}
+
+	return
+}
+
+
+func TestRTUTransportReadRTUFrame(t *testing.T) {
+	var rt		*rtuTransport
+	var p1, p2	net.Conn
+	var txchan	chan []byte
+	var err		error
+	var res		*pdu
+
+	txchan		= make(chan []byte, 2)
+	p1, p2		= net.Pipe()
+	go feedTestPipe(t, txchan, p1)
+
+
+	rt		= newRTUTransport(p2, "", 9600, 10 * time.Millisecond, nil)
+
+	// read a valid response (illegal data address)
+	txchan		<- []byte{
+		0x31, 0x82, // unit id and response code
+		0x02,       // exception code
+		0xc1, 0x6e, // CRC
+	}
+	res, err	= rt.readRTUFrame()
+	if err != nil {
+		t.Errorf("readRTUFrame() should have succeeded, got %v", err)
+	}
+	if res.unitId != 0x31 {
+		t.Errorf("expected 0x31 as unit id, got 0x%02x", res.unitId)
+	}
+	if res.functionCode != 0x82 {
+		t.Errorf("expected 0x82 as function code, got 0x%02x", res.functionCode)
+	}
+	if len(res.payload) != 1 {
+		t.Errorf("expected a length of 1, got %v", len(res.payload))
+	}
+	if res.payload[0] != 0x02 {
+		t.Errorf("expected {0x02} as payload, got {0x%02x}",
+			 res.payload[0])
+	}
+
+	// read a frame with a bad crc
+	txchan		<- []byte{
+		0x30, 0x82, // unit id and response code
+		0x12,       // exception code
+		0xc0, 0xa2, // CRC
+	}
+	res, err	= rt.readRTUFrame()
+	if err != ErrBadCRC {
+		t.Errorf("readRTUFrame() should have returned ErrBadCrc, got %v", err)
+	}
+
+	// read a longer, valid response
+	txchan		<- []byte{
+		0x31, 0x03, // unit id and response code
+		0x04,       // length
+		0x11, 0x22, // register #1
+		0x33, 0x44, // register #2
+		0x7b, 0xc5, // CRC
+	}
+	res, err	= rt.readRTUFrame()
+	if err != nil {
+		t.Errorf("readRTUFrame() should have succeeded, got %v", err)
+	}
+	if res.unitId != 0x31 {
+		t.Errorf("expected 0x31 as unit id, got 0x%02x", res.unitId)
+	}
+	if res.functionCode != 0x03 {
+		t.Errorf("expected 0x03 as function code, got 0x%02x", res.functionCode)
+	}
+	if len(res.payload) != 5 {
+		t.Errorf("expected a length of 5, got %v", len(res.payload))
+	}
+	for i, b := range []byte{
+		0x04,
+		0x11, 0x22,
+		0x33, 0x44,
+	} {
+		if res.payload[i] != b {
+			t.Errorf("expected 0x%02x at position %v, got 0x%02x",
+				 b, i, res.payload[i])
+		}
+	}
+
+	p1.Close()
+	p2.Close()
+
+	return
+}
+
+func feedTestPipe(t *testing.T, in chan []byte, out io.WriteCloser) {
+	var err		error
+	var txbuf	[]byte
+
+	for {
+		// grab a slice of bytes from the channel
+		txbuf = <-in
+
+		// write this slice to the pipe
+		_, err = out.Write(txbuf)
+		if err != nil {
+			t.Errorf("failed to write to test pipe: %v", err)
+			return
+		}
+	}
+
+	return
+}
+
+func TestModbusRTUSerialCharTime(t *testing.T) {
+	var d time.Duration
+
+	d = serialCharTime(38400)
+	// expect 11 bits at 38400bps: 11 * (1/38400) = 286.458uS
+	if d != time.Duration(286458) * time.Nanosecond {
+		t.Errorf("unexpected serial char duration: %v", d)
+	}
+
+	d = serialCharTime(19200)
+	// expect 11 bits at 19200bps: 11 * (1/19200) = 572.916uS
+	if d != time.Duration(572916) * time.Nanosecond {
+		t.Errorf("unexpected serial char duration: %v", d)
+	}
+
+	d = serialCharTime(9600)
+	// expect 11 bits at 9600bps: 11 * (1/9600) = 1.145833ms
+	if d != time.Duration(1145833) * time.Nanosecond {
+		t.Errorf("unexpected serial char duration: %v", d)
+	}
+
+	return
+}