DDE problems DMLERR_NOTPROCESSED 0x4009

I am trying to create a DDE client that works with yours DDE server, and I have some problems when I try to do a poke (write) to a boolean Modbus variable. All the other variables work fine. Is there a special way to send boolean values to an OPC tag variable? The DDE error is the following: DMLERR_NOTPROCESSED 0x4009

If the tag is in the TOP Server and defined as a boolean, then there isn't anything different that you do.

If the tag address your using is the device memory address like 10038, then you should still be OK as this is a default memory address.

If it is an output address, it needs to have the leading zero: 00423 to be a correct address.

If it's a holding register bit, like 400789.13 then you should add @boolean to the end of the address, like 400789.13@boolean.