Further specifications for ipEther232

Explanations

During the development phase, the compatibility between the “virtual“ serial driver and the
standard driver was a central issue for us. The Ethernet requires some minor
restrictions:

• Data is not transmitted in the network in bytes; instead, Ethernet blocks are formed.
  This might result in minor delays.
  
• There are Ethernet run-time delays.
  

The block forming function does not directly affect the application, but can help to
reduce network load.

Windows API

The "Application Programming Interface“ (API) driver is identical to the serial Windows driver.
Consequently, all applications using this interface can work with ipEther232.
All functions are available, but the timing might be slightly different.

UART

UART supports transmission speeds between 2.400 and 115.200 bauds. Higher baud rates might result in data loss if data is transmitted continuously.
7 or 8 data bits can be used.
The parities "None“, "Even“, "Odd“, "1“ and "0“ are supported.
7 bit data does not support the parity "None".(7N1).

Send

The time lapse between the “Writefile” call on the application and the appearance of the first byte at the interface amounts to approx. 5 milliseconds. All subsequent bytes of the task are shown at the interface without delay. In the case of synchronous write, the call is returned approx. 5 milliseconds after the last byte has appeared at the interface. For each function call, the "WriteFile“ function enters at least one packet to the Ethernet. If possible, only blocks should be written.

Receiving

Upon the reception of serial data, Ethernet blocks have to be assembled.
There are two timeouts available to do this for the ipEther232:

• Total read timeout
• Char distance

Fine-tuning might be required for time-critical applications as well.

The first byte starts the "Total read time" parameter. After completion, all characters
received until then are sent to the PC. This value must not fall short of the travel
time of the UDP packet in the Ethernet. Use the "ping" tool to determine the travel time. The default value for this parameter is 100 ms.

The "Character distance" is the maximum distance between two characters
received. If this value is exceeded, all characters received until then are sent to
the PC, even if the parameter did not run off "Total read timeout" yet.
The default value for this parameter is 10 ms.