Siemen's output card quandry

I've got a 6ES5 451-8MA11 It's a 8x24vdc digital output card. I've also got a 6ES5 441-8MA11 It too is an 8x24vdc output card. The 451 Siemens calls "Isolated" and the 441 they call "Non-isolated." My thought was that the isolated one had fused outputs and the non-isolated didn't. Can someone tell me where I'm going wrong here? I opened up the 451 and there are no replaceable fuses in there yet the red light marked "F" is on. The only other modules I have are inputs and they also have red LEDs marked "F." When the red LED is on, isn't that telling me I have a bad fuse?

-AJ-

I'm not familiar with your product but isolation has nothing
to do with overcurrent protection. When card is described as
"24point isolated output" it means that you have 24 outputs
which are not connected to each other. In other words, every
output can be used in different circuit.
For example, output 2 can be used in 24VDC circuit,
output 3 can be used say 120VAC circuit etc.
Non isolated points (inputs or outputs) have one side
connected together. If you run accross
card such as "16point output, 8 per common" it means that
you have two groups of 8 outputs. This is limiting factor
of course but reduces wiring.

Following is an example of 8outputs, 4per common:

 common0 ----+-----| |---- output0

             |

             +-----| |---- output1

             |

             +-----| |---- output2

             |

             +-----| |---- output3



 common1 ----+-----| |---- output4

             |

             +-----| |---- output5

             |

             +-----| |---- output6

             |

             +-----| |---- output7

Isolated means there is no electrical connection between the processor part and the outside world. The 441 has no opto-couplers, where the 451 does have them. This is basic knowledge. Check the parts about inputs and outputs in the introductory course on this fine site.

Kind regards,

i found out a problem when the dc current had to much ac on it.
the source was a simple transformer and a bridge and that does not work.
at that moment the red led goes on
it looks at the power supply if too low or too high it will lite and when power is wrong.