if ( param_getdec(Cmd, 0, &block) ) return usage_pcf7931_write();
if ( param_getdec(Cmd, 1, &bytepos) ) return usage_pcf7931_write();
- if ( (block > 7) || (bytepos > 3) ) return usage_pcf7931_write();
+ if ( (block > 7) || (bytepos > 15) ) return usage_pcf7931_write();
data = param_get8ex(Cmd, 2, 0, 16);