.PS
gen_init
  linewid = linewid*0.8
  circlerad = 0.35/2
  bw = boxwid/2
  bh = boxht/2
PID: [
  {"$r(s)$" above ljust}
  arrow
S1: circle
  line right "$e(s)$" above
  { arrow right ; box ht bh wid bw "$K_P$"
    arrow right linewid-circlerad ; S2: circle }
  { arrow up linewid then right ; box ht bh wid bw "$K_D s$"
    arrow to (S2,Here) then to S2.n }
  { arrow down linewid then right ; box ht bh wid bw "$K_I/s$"
    arrow to (S2,Here) then to S2.s }
  arrow right from S2.e "$u(s)$" above
  box "$G(s)$"
  arrow right ; "$y(s)$" above rjust at Here+(0,2pt__)
  arrow down boxht*5/4 from last arrow.c then left last arrow.c.x-S1.x \
    then to S1.s
  "$-\;$" below rjust
]
# "$PID$ control" below ljust at PID.sw+(0,-5pt__)
.PE