In node-red-contrib-cip-ethernet-ip node not able to read Micrologix 1400(Allen bradley PLC) Data

First PLC should be in run mode, so that node must appear not offline.
Second the tags should be defined in the node, same tags should be defined in the Allen Bradley PLC.

You may require the -pccc node to communicate with Micrologix 1400, the cip-ethernet-ip node is more suited for compactlogix and controllogix where you can define the tags. For Micrologix the tags are predefined.