Update all custom module related records when a contact is updated

Update all custom module related records when a contact is updated

Hi,

I'm trying to write a custom function which will run whenever a 'Contact' is updated - it should update all items within a related list (called ProductContacts which is CustomModule1).  How do I retrieve the ID value to pass into updateRecord?  I've tried CustomModule1_ID and ID but the idStr parameter is always returning as null



Could you provide some assistance to allow me to loop through all my customModule record, update one field and save the changes?

Thanks,
Beth