Linear Encoder Maho600

I all, I have a MAHO MH600E cnc 432, but no can move the x axis, this say Alarm X02: (Alarm measuring system fault), i suspect what is the encoder model AE LS 403 Heidenhain.
Seeing the datasheet this have 1Vpp power suply of 5v, resolution is my doubt say 1um/0.005um, if anyone knew which of these two is the correct.
other data is Grating Period 20um, and System Accuracy Grade of +-5um, here is other doubt, the diference between resolution and accuracy, why is the difference so much?

I thought that the precision should be less than the resolution.

This alarm refers to an encoder problem?, should I change this?

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Renato

Other than the .005 um, those numbers make sense: a 20 um pitch scale with a 20 X interpolator will provide 1um resolution and the scale is rated +-5 um/meter accuracy

OK thanks, refer a 5um/meter, it is ok.

Renato