You cannot set a break point during program execution. Halt a program temporarily and then set a break point.
[Reference information] The DTU8 debugger allows setting of PC matching break during program execution. Changing a break condition during program execution using this function suspends the program execution in the background. The program is restarted after a break condition is changed.
The setting procedure is as follows. (1) Select [Environment settings] from the [Tools] menu, open the [Other] tab and select the “Enable changing RAM values and break conditions during emulation” check box. Then click the OK button. (2) Select [Break Conditions] from the [Run] menu to display the [Break Conditions] dialog box. (3) Select the “PC match break” check box, specify a break address and then click the OK button.