There is no specific law regarding visitation. Generally, the non-custodial parent is entitled to visitation with the children of the marriage. That visitation can be extensive or not. It is generally up to the parties themselves to arrange a schedule. In the event they cannot do so, the court will order a schedule, which will generally include overnight weekend visitation.
The custodial parent is required to encourage visitation with non-custodial parent. Recent cases have held that the failure to foster a relationship with the non-custodial parent can be a ground for a change of custody.