I/O 7i64

Peter,

I have the following connection

24 VDC source

+ (24VDC) TB2 (1)
- (0vdc) TB2 (8)

measurement sensor proximity

not activated.

TB2 (8) ==> INPUT 7I77 = 9VDC

activated

TB2 (8) ==> INPUT 7I77 = 20.1

measurement limit switch

not activated.

TB2 (8) ==> INPUT 7I77 = 0VDC

activated

TB2 (8) ==> INPUT 7I77 = 24 VDC

Looks like the proximity sensors are not fully off when not activated.
(are these really 2 wire sensors?)

Do you have the specifications of the proximity switches?

Without more information (and they are truly 2 terminal devices)
I would guess they need a lower load resistance
so you might need to add a 1K 1W resistor from each 7I77 input that's
connected to a proximity switch to 7I77 input GND.

Andy I have the two cards the 7i77 and 7i64.

I used the inputs 7i77 for home and limit switch X and Z.

think this poorly connected?

but all sensors have the same problem.

connecting it to think 7i64 not present that problem?

The 7I64 will not work either. These 2 wire proximity sensors need a low value load resistance because they need power whether on or off. They get power when 'off' by leaking current. Notice that the limit switches have a 24V output swing and work fine with the 7I77 (and will work fine with the 7I64) but the proximity sensors output only swings from 9V to 20V at the 7I77 (20K pulldown) inputs.

The 9V is a marginal low so does not work. The only solution I can see is to put pull down resistors between the 7I77 inputs used for these 2 wire proximity sensors and GND (1K 1W should do)

peter works perfect. with resistance "1K 1W"

Thank you.