Read pfield values from any active instrument instance


pread can be used to query the pfield value of a running instance (possibly a fractional instrument number) of an instrument. Together with pwrite it can be used to establish a two-way communication between two running instances of any two instruments.

It no instance is found that matches the given instrument number, the output value is set to inotfound.


  • If no matching instance is found, pread returns inotfound. Reporting starts at the moment a matching instance is found.
  • To avoid a continuous search, set instrnum as negative number. In this case, a matching instance is searched only once, and, if not found, this opcode becomes a noop
  • If an instance is found and stops, pread returns inotfound from the moment the instance stops and no new instance is searched.


ivalue    pread instrnum, iindex, inotfound=-1
kvalue    pread instrnum, iindex, inotfound=-1
kvalue    pread instrnum, kindex, inotfound=-1

ivalues[] pread instrnum, iindexes[], inotfound=-1
kvalues[] pread instrnum, iindexes[], inotfound=-1


  • instrnum (i): the (fractional) instrument number to modify
  • iindex / kindex: the index of the pfield to read.
  • inotfound: the value to return if instrnum is not found. To avoid misinterpretation, this value should be different than any expected value of the pfield


  • ivalue / kvalue: the current value of the given pfield. Will be inotfound if no matching instance has been found.

Execution Time

  • Init (if output is of i-type)
  • Performance (if output is of k-type)







  Example file for pread

  ivalue pread instrnum, index  [, inotfound=-1]
  kvalue pread instrnum, kindex [, inotfound=-1]

  pread reads a pfield value from an active instrument
  Returns inotfound if instrnum is not active

  Raises a performance error if index is out of range


instr 1
  prints "instr 1. p4=%f, p5=%f\n", p4, p5

instr 2
  ip1 = p4
  ip4 pread ip1, 4
  prints "Inside instr 2. Instance p1=%f, p4=%f\n", ip1, ip4
  pwrite ip1, 4, ip4*2

instr 4
  ip1 = p4
  iindex[] fillarray 4, 5
  ivals[] pread ip1, iindex
  prints "Inside instr 4, reading p4 and p5 as array"
  printarray ivals


i 1.01 0   2 44   45
i 2    1   0 1.01
i 4    1.5 0 1.01


See also


Eduardo Moguillansky, 2019