The only rule is that you must have 730 days in Canada in your first 5 years as a PR counting from the day you landed in Canada and after you have been a PR for more than 5 years, you need 730 days in any rolling 5 year period.
730 days = 2 years and therefore you are allowed up to 3 years outside Canada at a time. However, if you spend 3 years outside Canada in one go, you will then have to come back and stay in Canada for 2 years straight to make up.
Leon thanks for the REPLY . Another question in my mind that comes now is that if I go back without PR card to my home country and if my card will not come to the given address than IS THERE ANY TIME LIMIT TO APPLY FOR TRAVEL DOCUMENT AND WHAT'S THE EXPIRY DATE OF TRAVEL DOCUMENT.
You must meet the conditions of 730 days in Canada or still able to meet 730 days in Canada in your first 5 years in order to get a travel document so that is your time limit.
Keep in mind that the processing time of a travel document can sometimes be weeks or even months so apply for it in time before you want to return. From what I have heard, they tend to be valid for 6 months but you should ask the Canadian embassy where you are about that before you apply.
