The placement of both the transmitter and receivers within the Project should be considered carefully when using the Radio Links components. All non-electrical components in a PSCAD Project, are essentially a graphical representation of structured Fortran code (see System Dynamics for more details).
All components within a particular Module (including the Main Page) are arranged depending on their connectivity to each other, and then a Fortran file is built to describe the contents of the Module. This Fortran code is then read from top to bottom each time step by EMTDC. A sequence also exists involving Modules themselves, which are the Fortran equivalent of subroutines. If several Modules exist within one page, then their corresponding CALL statements will also be placed in sequence depending on what they are connected to (where their arguments are defined).
Keeping this in mind, one conclusion can come of this: The signal output by any receiver defined in sequence before its transmitter, will be delayed by one time step. For example, consider a Radio Link transmitting a global variable to two receivers, located in different areas of the Project. Receiver 1 appears in sequence before the transmitter, whereas Receiver 2 follows the transmitter:
Plotting the receiver output data would show the Receiver 1 output delaying Receiver 2 by a single time step.
Note that the above example assumes that all Radio Links are defined within the a single EMTDC Dynamic Subroutine (i.e. DSDYN or DSOUT). If the transmitters and receivers are interspersed between both DSDYN and DSOUT, then further consideration is required. According to the EMTDC Program Structure, DSDYN is called before DSOUT every time step. When the end of the DSOUT code is reached, the time step is incremented by Dt, and the process begins again at the beginning of DSDYN. If any transmitters are located in DSOUT, then corresponding receivers located in DSDYN will be delayed by a single time step.
