Hi,
You can define, Purchasing groups under the menu path
SPRO-->MATERIAL MANAGEMENT-->PURCHASING-->CREATE PURCHASING GROUPS
Maintain the necessary details like
Purchase group key
Description
Tel Phone
Now under the messages node, you can assign the printers to respective purhasing groups
SPRO-->MATERIAL MANAGEMENT-->PURCHASING-->MESSAGES-->ASSIGN OUTPUT DEVICES TO PURCHASING GROUPS
hope it is clear
regards,
santosh