Greetings AB guys!
I am the principle programmer for a SCADA server ControlLogix driver. I implemented an Explicit Connected Messaging solution using the EIP/CIP message protocol that generates the byte stream for the TCPIP buffer. Driver is unmanaged C++ code. We are successfully reading and writing all data types except strings. The public documentation from AB on Data Access 5000, does not address accessing strings however we have customers that need to. So far my attempts are not working as I thought they would with some trial and error.
Using the Write Service (0x4D), I attempt to write HELLO to the tag called Z_PRD_NM[3].DATA
4D 09 91 08 5A 5F 50 52 44 5F 4E 4D 28 03 91 04 44 41 54 41 C2 00 52 00 48 45 4C 4C 4F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
The PLC responds with a error 5.
If I attempt to read the same tag (Z_PRD_NM[3]), the PLC returns a data type of C4 and an Int32 value. I would appreciate any help here. ;)