Why isn't there every a "PanelView Firmware" category at the pub on Trivia Night ? I'd clean up !
You're correct, Alan, that DF1 and DH-485 are different and incompatible protocols, even when they're carried on the same physical signaling system (RS-232). Just converting the signaling system from RS-232 to RS-485 doesn't change the protocol.
But wait, there's more, as long as you don't mind voiding the warranty.
PanelViews have a "hardware string" built into their boot firmware that will inform the firmware download utility what mainboard and communications daughterboard revisions are present. This helps prevent you from loading ControlNet firmware into a DH+ PanelView and creating an expensive doorstop.
On the DF1 and DH-485(RS232) terminals, the hardware string is the same. You can download DH-485(RS-232) firmware into a DF1 PanelView terminal. The two serial ports (printer and comms port) will now be swapped in their assignments, but the former Printer port will now run DH-485 protocol.
example part numbers:
2711-T10C16 DF1 with Printer Port
2711-T10C9 DH485 (RS232) with Printer Port
This is not true of the DH-485(RS-485) firmware ! That hardware (the 2711-T10C3 terminal, for example) is different and that firmware won't run on a PanelView that started life with DF1 !
Since this is a newer PV terminal, you might not want to void it's warranty, but if you do I recommend using a Flash memory card instead of the difficult DOS utility.
Once you've changed the protocol, you will need to convert to RS-485 electrical format to plug into a DH-485 network, and for that you do use the 1761-NET-AIC (called the AIC+) module.
Cheers,
Eddie