Used for analog output function selection "terminal output voltage". Analog output voltage 10 V corresponds to 1.2 times of [b0.20], for example: [b0.20]=220 V, the terminal output voltage 0 ~ 264 V corresponds to 0 / 2 ~ 10 V, see descriptions in parameter [E1.30] ~ [E1.32]. b0.21 Carrier frequency