Configure Serial Multidrop Settings
For multi-drop networks, the SCADAPack x70 device can perform ‘media collision avoidance’, whereby transmissions are checked for collisions with another transmission on the network. If a collision is detected, the SCADAPack x70 device re-attempts the transmission, after a delay.
Use the fields within the Serial Multidrop Settings section of the Serial tab to define the operational characteristics when a SCADAPack x70 device uses a multi-dropped network.
These parameters are only available when the Port Mode within a Port Function is set to RS232 (RTS) Keyed, (see Device Configuration Serial Port Tabs)
Each field requires an interval entry in the OPC Time Format. You can enter the value directly in the field, or use the Interval window (accessed via the field's browse button) to specify the required value.
Specify the delay that is required between the transmission media being activated and the actual transmission of data. This delay allows the transmission device (for example, a radio unit) to activate its transmitter. The default is 60 milliseconds.
Specify the maximum additional delay that the SCADAPack x70 device adds to the Fixed Delay, before sending data on the transmission media, once the SCADAPack x70 device has detected a transmission collision. The SCADAPack x70 device will add a random delay of any length up to and including this value. The default is 100 milliseconds.
Specify the amount of time that has to elapse between the last byte being sent and the Request to Sent (RTS) signal being turned off. The default is 20 milliseconds.
Specify the fixed time delay for which the SCADAPack x70 device waits, before attempting a data transmission, once it has detected a transmission collision. Before the transmission is attempted, the SCADAPack x70 device adds an additional random delay (seeMax Random Delay above). The default is 0 milliseconds.
If both the Fixed Delay and Maximum Random Delay are set to zero, the SCADAPack x70 device does not perform any collision avoidance.
Specify the period for which the SCADAPack x70 device is to delay transmission of any data prior to activating the transmission device. A delay other than zero may be required where a radio repeater is slow to drop its carrier and the SCADAPack x70 device tries to respond too quickly to a request to send data. The default is 0 milliseconds.