7550RTU Pulse input, minimum voltage for correct operation ?

[Rich_Lannaghan]

Hi,

Posted this across on hardware but seems more going on over here !

Does anybody know what the minimum voltage that the 7550RTU can take on a digital input from a pulse meter ?

The manual states external supply of maximum 130VDC but what is the minimum for the input to operate correctly ?

Cheers

[Tom_Stevenson]

The hardware forum is the right place for this question Richard.  Someone in the community may know, but I am going to bump your original post to the top.

Tom

[Rich_Lannaghan]

Tom, thanks, no answer as yet, i would got to UK tech support but think they will just go with the manual spec.

[sesa181247_brid]

The minimum external voltage would be zero, and it would be configured as in the diagram on the left for internal excitation.

[Rich_Lannaghan]

Mark, sorry, not sure i follow, the voltage out of SCOM would be 30VDC in that diagram ?

I need to interface to a gas meter to read pulses, the maximum that can be on that is 20VDC, hence my question what is the minimum voltage of external excitation could the input receive to count a pulse ?

Can you suggest the correct connection of the DI on the 7550 for operation like is detailed below in the gas meter manual ?