Features:
• Fully assembled and tested.
• Fully powered from USB
• For 12V/24V DC 15A or 120V/220V AC at 10A max.
• Can be used with  LabVIEW, ProfiLab, DAQFactory, TestPoint, DASYLab, VEE

Complete including:
- One USB relay board

Dimensions (PCB board) :
90 mm / 35 mm

Links:
Manual - http://www.sigma-shop.com/manuals/USB1RELAY_manual.pdf
Drivers - http://www.ftdichip.com/Drivers/VCP.htm
Support forum - http://www.sigma-shop.com/board/

Drivers are available to work with the following operating systems:
Windows Vista x64, Windows XP x64, Windows Server 2003 x64, Windows Vista,
Windows XP, Windows Server 2003, Windows 2000, Windows ME, Windows 98,
Linux, Mac OS X, Mac OS 9, Mac OS 8, Windows CE.NET (Version 4.2 and greater)

Communication Parameters:
8 Data, 1 Stop, No Parity
Baud rate : 9600

Commands:
OFF command: FF 01 00 (HEX) or 255 1 0 (DEC)
ON command: FF 01 01 (HEX) or 255 1 1 (DEC)


Sample VB6 code :
----------------------------
Private Sub cmdOff_Click()
With MSComm1
'make sure the serial port is open
If .PortOpen = False Then .PortOpen = True
'send the data
.Output = Chr$(255)
.Output = Chr$(1)
.Output = Chr$(0)
End With 'MSComm1
End Sub
Private Sub cmdOn_Click()
With MSComm1
'make sure the serial port is open
If .PortOpen = False Then .PortOpen = True
'send the data
.Output = Chr$(255)
.Output = Chr$(1)
.Output = Chr$(1)
End With 'MSComm1
End Sub
----------------------------

Sample C# code:
----------------------------
private void button1_ON_Click(object sender, EventArgs e)
    {
    serialPort1.Write(new byte[] { 0xFF, 0x01, 0x01 }, 0, 3);
    }
private void button1_OFF_Click(object sender, EventArgs e)
    {
serialPort1.Write(new byte[] { 0xFF, 0x01, 0x00 }, 0, 3);
    }  
----------------------------

Linux:
----------------------------
The old kernel's "echo" commands:
   echo $'xFFx01x01' > ttyUSB0
   the relay 1 go ON.
   echo $'xFFx01x00' > ttyUSB0
   the relay 1 go OFF.
----------------------------
The new kernel's "echo" commands:
   echo -e 'xFFx01x01' > /dev/ttyUSB0
   the relay 1 go ON.
   echo -e 'xFFx01x00' > /dev/ttyUSB0
   the relay 1 go OFF.
----------------------------