unable to connect to 89c668

[Angel Morales]

I have recently adquiered a PLC with a 89c668 microcontroller. I have tried to program it with Flash Magic and WIN ISP and all my efforts have failed.
I allways obtained the same messages: "Unable to connect at the secified baud rate" and "No response to "U" ".
The parameters employed are:
Baud rate: 9600
Device: 89c668
Ocs. Freq.: 22.1184

DTR and RTS option is not enable (PLC uses only RxD, TxD and ground pins) and I don

[Andy Ayre]

You want to avoid using any handshaking at all. It's not supported by the BootROM.

What happens when you follow the steps in Flash Magic Application Note 4?