Serial (RS232) Interface Card
An RS232 interface, general purpose I/O Card that connects to a free serial
port on any PC Compatible, with a range of DIP switch selectable Baud rates
(600 - 76800: 38400 is max in VB6 : Note, that this is somewhat faster than some
USB boards that have a throughput rate of 20ms, ie 50Hz ), Prototyping area,
onboard voltage regulator for field applications, 40 way IDC connector for
external daughterboard user circuits, and handshaking signals for input/output.
The 8 bit output port is supported by a positive strobe to enable latching of
multibyte data, whilst the 8 bit input port has a negative strobe associated
with it. These two handshaking signals enable extremely easy interfacing to
ADC and DAC and other chips that have a data input and a clock requirement,
for example, Frequency Synthesisers. Applications covered in the documentation
include Temperature measurement (A/D Conversion), Multichannel I/O, Steppor
Motor control, and D/A conversion. The excellent multichannel AC Power control
App is no longer supported due to current legal restrictions. In any case
wiring up an optocoupled Triac controller is trivial, and is your responsiblity
to get it right. One customer has had 64 AC Power channels controlled per card,
without any problems.
Visual Basic 6 was originally used for the applications development (because of convenience). However, now that all our new software is written for .net, C Sharp is used for most of our applications development. Below is some sample code for Visual C# 2005 and 2008.
private void dostuff()
{
int mybaudrate = 9600;//Note, the card supports up to 76800.
byte recdata;
SerialPort port = new SerialPort("COM1", mybaudrate, Parity.None, 8, StopBits.One);
port.Open();
byte[] sequence = new byte[] { 0x0A, 0xE2, 0xFF, 0xAB, 0x0A, 0xE2, 0xFF, 0xAB,
0x0A, 0xE2, 0xFF, 0xAB, 0x0A, 0xE2, 0xFF, 0xAB};
port.Write(sequence, 0, 16);//Write a group of bytes
port.Write(new byte[] { 0xFF }, 0, 1);//Write a single byte
recdata = (byte)port.ReadByte(); //Read a received byte
port.Write(new byte[] { 0x55 }, 0, 1);//Write another byte
recdata = (byte)port.ReadByte(); //Read another received byte
label1.Text = "Data Sequence Uploaded..." + recdata;
port.Close();
}
} The following sample applications are included in the CD documentation.
Example ADC Circuit
This uses the LM35DZ Temperature sensor to measure Temperature within a range of
+2°C to 150°C.
Example Steppor Motor Interface
Driven with an open collector 7407. For
higher power handling use a VFET array.
Key Benefits
Software (source) Visual Basic 6, and CSharp.
Null modem cable included.
Documentation (on CD) covers ADC, DAC, Steppor motor
control and multichannel applications.
Pricing, £79 per unit.
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