Help with global variables

I’ve created some global char variables in my main program file. I would like to manipulate them in a library function. When I try to compile the program I get the following error:

line 405 : ERROR MODBUS_SLAVE_RCM3610.LIB : Assignment to read-only variable not allowed.

What am I doing wrong?

Thank you

It should work, works in my program.
Please show where you have declared your global variable in your main program, as well as where you are using it.

Thank you for the reply.

I used different capitalization of the variable in the library file. It works fine now.