Ok, Ill give a description of it.

As said before these will go into disco lights. There will be at least 14 lights that all have to run together. The addressing system allows for about 200 lights but realisticly i will never have more than 30. They are connected using 3 pin DMX cables. Inside each light the in/out XLR sockets are wired together (asif the light wasnt even there). Most of the lights will be connected with 1 meter cables but PC>first light and stageleft>stageright could be upto 20 meters

The DataOut pin is only so the lights can send info back to the PC. Things like its ID number so the PC can check all the lights are responding etc.

DataIn is where the data comes into the lights from the PC to tell them what to do.

There is a button on the back of each light. When you press it it checks if the PC is sending an ID. If it is then it changes its own ID to the one the PC sent. If the PC doesnt send an ID then it turns itself into a master where it sends data out of DataIn to all the other lights

The lights need to support PWM for fading.

They do need to work with some existing controllers too. The existing ones are RS232 but they dont need to send data to these so the RS232 output from the PC could go directly to the existing ones then into a converter for RS485/422 and onto the new ones.

Since there will be at least 14 lights i think that means i need 485 and not 422. Will i be able to buy an RS232<>RS485 converter and simply swap the MAX232 chips for a MAX485 (if they existst)? Ive not actually made the circuits yet so i can change pins around if i need to