David Torrens
Member
We are using 6ES7 331-7KF01-0AB0 * Input "Optically Isolated Input Modules.
I have found that if there is a large difference in potential to ground between adjacent inputs then all the inputs in that group read as full scale. This is regardless of what the differential voltage is between the two wires of the input.
Is this a know problem?
I notice that AI 6ES7 331-7KF01-0AB0 is no longer listed in the Siemens catalogue.
However I have an old catalogue and it states "Permissible Input Voltage for Voltage input" 20 Volts.
Now I am not sure what that actually means in practice.
Does it mean that an adjacent input being more than 20 volts different will cause a malfunction OR
does it mean the maximum differential voltage applied to the two input terminals is 20 volts Dc ?
What are the restrictions on the relative voltages to ground of adjacent inputs?
What I would expect is that if I have a system stating that the Opto Isolation has been tested to 500VDC that each input can be at up to 500V DC relative to any other input and the module will work correctly.
.
I have found that if there is a large difference in potential to ground between adjacent inputs then all the inputs in that group read as full scale. This is regardless of what the differential voltage is between the two wires of the input.
Is this a know problem?
I notice that AI 6ES7 331-7KF01-0AB0 is no longer listed in the Siemens catalogue.
However I have an old catalogue and it states "Permissible Input Voltage for Voltage input" 20 Volts.
Now I am not sure what that actually means in practice.
Does it mean that an adjacent input being more than 20 volts different will cause a malfunction OR
does it mean the maximum differential voltage applied to the two input terminals is 20 volts Dc ?
What are the restrictions on the relative voltages to ground of adjacent inputs?
What I would expect is that if I have a system stating that the Opto Isolation has been tested to 500VDC that each input can be at up to 500V DC relative to any other input and the module will work correctly.
.