Export excise invoice should have different currency from Company currency

Dear All,

Our company started export division recently.

Upto commercial invoice all the documents will be maintained in *Company code currency (INR)* only.

In the excise invoice, we want to maintain the currency as per the "Purchase Order".

Because, sometimes we used to get the Purchase Order in INR sometimes in "EURO".

What is the configuration required for this.

Kindly suggest.

Regards,

Mullairaja