Stimulation backend mpi - Receive stimulation parameters via MPI


This stimulation backend is only available if NEST was compiled with support for MPI.

The mpi stimulation backend collects data from MPI channels and updates stimulation devices just before each run. This is useful for co-simulation or for receiving stimuli from external software.

There are two ways to set the MPI port. If both are set, option A has precedence

  1. The address is supplied via the recording backends “mpi_address” status property.

  2. The name of the MPI port to send data to is read from a file for each device configured to use this backend. The file needs to be named according to the following pattern:


The data_path and data_prefix are global kernel properties, while label is a property of the device in question and node_id its node ID. This path can only be set outside of a Run context (i.e. after Prepare() has been called, but Cleanup() has not).

Communication Protocol

The following protocol is used to exchange information between both MPI processes. The protocol is described using the following format for the MPI messages: (value, number, type, source/destination, tag)

  1. Prepare : Connection of MPI port include in one file (see below)

  2. Run begin : Send start run (true, 1, CXX_BOOL, 0, 0)

  3. Run begin : Send the id of the device to update (node_id, 1, INT, 0, 0)

  4. Run begin : Receive shape of the data (shape, 1, INT, 0, 0)

  5. Run begin : Receive the data for updating the device (data, shape, DOUBLE, 0, 0)

  6. Run end : Send at each ending of the run (true, 1, CXX_BOOL, 0, 1)

  7. Cleanup : Send at this en of the simulation (true, 1, CXX_BOOL, 0, 2)

Data format

The format of the data depends on the exact type of stimulation device.