I have Critical Problem in Vijeo Citect V7.4 , I face problem in the compiling if I try to write Text Tag in the address field , the only way to avoid to bug is to type numeric address which is not beneficial for me.
I see that you are trying to use tagname inside address field for variable tags. Infact its not at all allowed to use tags inside address field except for OFSOPC tags which is a tag based protocol and address and OPC communication works with tag based addressing. If you see example IOdevice type is OPC thats why you can use tag based address.
I feel you have IOdevice type as Modbus or modbus ethernet protocol and addressing for modbus is like 40001 etc.. and you cannot use tags for thats. Thats why when you configure register address of modbus type you dont get error.
Refer citect driver help which explains about different protocols and there addressing formats.
Incase if you dont want to use equipment based addressing inside citect there is way to disable it . Go to the project editor -----> Tools --> options and uncheck "Disable equipment equipment when populating tag list " This will allow you to see simple tags configured from project editor and there is no need to configure equipments etc.