Micrologix 1400 faults with expansion modules

Hello all,

I have a micrologix 1400 with 3 expansion modules, an Analog Input (1762-IF4), a relay output (1762-OW8)and an Analog Output (1762-OF4).

I can only hook two modules at a time...whenever I hook up the third module, the PLC FAULT light and POWER light flash intermittently for about 1sec....the ethernet network lights also flash for about 1 second intermittently....the plc never boots up

I can mix and match the modules, but only two work..never three....so nothing seem to be wrong with the modules themselves...

Only other thing to note, is that I have these hooked up on a desk, for programming, not on a DIN rail...so maybe grounding is a problem?

any idea what is wrong?

thanks,
Ian

Or a bad power supply

Are you using a proper Bus Terminator?

Stu....

Ok, I just realized something..

The Analog Output Module works SOMETIMES....the other two modules work all of the time, so I guess the problem is with the Analog output module...

I checked on the bus terminator, but I don't see anything like that for the micrologix 1400..good suggestion though! thanks.

I checked on the bus terminator, but I don't see anything like that for the micrologix 1400..good suggestion though! thanks.

Click to expand...

Sorry, I should have checked. I am used to the 1500. According to AB, the 1762 I/O doesn't require an End Cap with the 1100/1200/1400.

Stu....

What is a bus terminator?

I see references to a "bus terminator" for 1762 I/O modules for the Micrologix 1400.
I am doing a project using a ML 1400 and just added an -OW8: relay output module.
Do I need some other component called a "bus terminator" ? I know some systems needs end-of-line resistors for impedance terminations. Is this the case here?

djacob said:

I see references to a "bus terminator" for 1762 I/O modules for the Micrologix 1400.
I am doing a project using a ML 1400 and just added an -OW8: relay output module.
Do I need some other component called a "bus terminator" ? I know some systems needs end-of-line resistors for impedance terminations. Is this the case here?

Click to expand...

No you don't need a bus terminator for the 1400.