I am currently working on a small project as an engineering trainee, where i am to continue on the development of a DMX tool to help with the testing of intelligent light fixtures at my workplace.
The project is written in C# and uses the managed FTD2XX_NET.dll wrapper available from Ftdichip website as well as using the Enttec DMX USB PRO Mk2 as interface between the PC and light fixture.
The whole point of the DMX Tool is to be able to send DMX packets with different parameters e.g. sending DMX with a user setable start code or packet size, as well as customizable port settings e.g. different baud rates, to see how a given light fixture will run with non-standard settings for testing purposes.
I have partly succeeded in implementing the above features, and I have now hit a brick wall...
The DMX Tool is required to be able to run with two different modes:
Continuous mode and Single Packet Mode.
As stated earlier, I am able to successfully send the given DMX packet, but only continuously. I have searched the deepest and darkest corners of the web to find a explanation as to how the Enttec DMX USB PRO Mk2 actually works internally and how to stop this seemingly continuous data transmission, but have gotten nowhere.
And this leads to the real questions:
How does the Enttec DMX USB PRO Mk2 handle the USB-RS232 serial connection? Is it possible to programatically bypass this continuous data transmission to be able to send a single DMX data packet and if so, how?
I can't see any useful datasheets, but you might want to try using a tool like RealTerm to monitor the virtual COM port FTDI uses while using the standard software.
If you haven't seen the DMX box sending single packets at all, it may be worthwhile opening it up to see if there's a jumper or DIP switch that needs changing.
Sorry I can't be more help than that.