Serial Bindings Dimmer config

I am new to openhab, i want control my dimmer via serial. I need help to understand how to config dimmer increaseValue and decreaseValue new serial binding (openhab 3). My device get serial massage like spot1(bright=VALUE)…
Can get item dimmer value and using dynamic in order to send dimmer i want??
Type dimmer : serialDimmer [increaseValue=“spot1(bright=[%s])\n”,decreaseValue=“spot1(bright=[%s])\n”,onValue=“spot1(ON)\n”, offValue=“spot1(OFF)\n”]

No, you don’t have access to the existing Item state in the channel settings to deal with INCREASE/DECREASE commands.
If your device does not support being sent this kind of step-up/step-down commands, then you can’t use them.

You could intercept these commands in a rule, have that workout current+5 or whatever, and send a numeric target to your device.

OK thank you… I will using rule

dimmer : serialDimmer [increaseValue=“spot1(bright=[%s])\n”,decreaseValue=“spot1(bright=[%s])\n”,onValue=“spot1(ON)\n”, offValue=“spot1(OFF)\n”]