if ( param_getdec(Cmd, 0, &block) ) return usage_pcf7931_write();
if ( param_getdec(Cmd, 1, &bytepos) ) return usage_pcf7931_write();
if ( param_getdec(Cmd, 0, &block) ) return usage_pcf7931_write();
if ( param_getdec(Cmd, 1, &bytepos) ) return usage_pcf7931_write();