First it is important to know what the function and role of Child Protective Services, or CPS, is in order to better understand what rights you have should you end up in a situation where CPS contacts you. The function of CPS is to investigate reports of child abuse or neglect, meaning someone has made an anonymous report that abuse or neglect is occurring, and now a caseworker for CPS is charged by law with investigating whether there are any threats to the safety of the children in the home. You can find out more on the DFPS website.
If you are contacted by a caseworker and they wish to speak with you, come see your home, or meet with your children, know that you have a right to have an attorney present. However, at the very outset of the investigation you do not have a legal right to have an attorney appointed to you, because at the outset this is just an investigation and not an actual legal case.
The department may advise you that having an attorney is not necessary but it is important that you understand that whatever is said, found, or uncovered in an investigation could possibly be used against you in a future legal case or possible criminal charges.