to_ch_num
usable_chs = MULTIPLEX_CH_MAX - to_ch_num(val);
if (to_ch_num(val) > usable_chs) {
to_ch_num(val), usable_chs);
usable_chs = MULTIPLEX_CH_MAX - to_ch_num(val);
if (to_ch_num(val) > usable_chs) {
to_ch_num(val), usable_chs);