1. Login in with Fresa Gold, Navigate to Accounts-> All Vouchers and Open an purchase invoice voucher which is in Posted status (Fig.1).
2. Now click Generate Payment Voucher button (Fig.2).
3. Select the Book (payment type), Bank/Cash A/C and click Save (Fig.3)
4. Now the Payment Voucher will be generated (Fig.4)
5. Now Change the Payment voucher status as Posted and Check the purchase invoice, the O/S will be cleared (Fig.5)&(Fig.6)
Hope you got an idea about how to generate payment voucher from an purchase invoice.