hi,
typing setserial -g /dev/ttyS? gives:
/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4 /dev/ttyS1, UART: unknown, Port: 0x02f8, IRQ: 3 /dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4 /dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3
Which seems okay?
Yes, they look ok, except no UART is specified for 1, 2, 3. Although it could be connected to 0 and the UART is correct. Check the UPS specifications to find out its UART. You can correct this with setserial. You can also use setserial to automatically configure the serial ports ("man setserial" for further information).
However, cat /dev/ttyS0 gives absolutely nothing, no chatter, nothing.
It would give nothing. Assuming the UPS understands some commands in the same way as a modem, you could just echo commands to it and this will be displayed on the screen with cat /dev/ttyS0. For example, for a modem: On console 1 ([CTRL] [ALT] [F1]), login as root and then execute: cat /dev/ttyS0 On console 2 ([CTRL] [ALT] [F2]), login as root and then execute: echo "AT" > /dev/ttyS0 and assuming the modem knows AT commands then it will reply and show the reply on console 1. So, assuming a UPS has some standard commands (refer to the manufacturer's manual) then it will respond to commands sent by echo and display the output on console 1 -- /Paul "It's not about the ending, it's about the journey." - Lex Luthor