Magnetic Reeds

I am hooking up a magnetic reed switch for a air cylinder to the input on micrologix 1000 and I am using 24VDC supplied on the PLC. I must not exceed 400ma.for the reed. This reed has a light for it to show when it is energized. I was wanting to know how many Milli Amps is the input. I want to hook it direct without using a relay. THANKS!!!!

I would suggest that you go to the manufacturer's website or look at the sheet that came with the reed switch to determine how many miliamps is required.

The Manufaturer listing says 150mA at 158 degrees and 400 mA at 77 degrees. 120ac/110vdc SPST Normally Open 2-wire. 1.0 millisecond time.

See Pic below. With an input impedance of 3K ohms I don't think your going to have a problem.

I want to hook it direct without using a relay. THANKS!!!![/QUOTE]

If the reed switch has an LED, then it is most likely a solid state switch and needs the 24VDC to operate. Don't know what the relay you mentioned is for.

just go ahead and hook it up.
PLC inputs have impedance in the order of 2-3k and you don't need a relay,
you are expected to wire it directly...

if the reedswitch is 2-wire device, connect:
brown wire to positive supply,
blue wire to PLC input

if it is 3-wire device:
brown to positive supply (24VDC),
black to PLC input,
blue to negative supply

if the PLC expects sinking inputs (usually seen on Japaneese PLCs), then 3-wire wiring is the same but 2-wire is slightly different:
blue wire to negative supply
brown wire to PLC input

if the switch works (as indicated by input LED on PLC) but the LED on sensor is always off,
it means you swapped the sensor wires (blue wired to +24 and brow wired to PLC input)