Siemens SIMATIC S7 System Manual page 529

Network 10: Capture the interval timer and then change to the "Idle Wait" state to delay until
it is time to transmit again.
Network 11: State "Idle Wait"...
Stay in this state for the number of milliseconds specified (IdleTimeDelay).
Network 12: Calculate the time since you entered the "Idle" state and, if this is greater than
the "IdleTimeDelay" value, change the state to the "Transmit" state.
Network 13: State 'Transmit"...
Network 14: Create the message to send to the passive device.
For the test program, fill the send buffer with 40 bytes (20 words). Write the number of bytes
to send into a variable so that you can use the same value in the "TransmitWait" state.
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
9.4 Open user communication library
Libraries
529