134 | Managing the Radio
Aprisa SRi User Manual 1.1.0
Optimization
The Aprisa SRi provides a Half Duplex radio channel with variable latency. Error free transport of the
protocol can be achieved through specific serial traffic configuration settings, which are dependent on the
radio RF configuration, Mirrored Bits® devices and network characteristics.
Under some scenarios limited Ethernet transport may be supported without impacting Mirrored Bits®
operation. If the network can tolerate occasional ROK errors Ethernet support may be increased. The level
of impact on Mirrored Bits® is related to radio settings and the specifics of the Ethernet traffic including
size and frequency of the Ethernet packets.
When attempting to configure the radios to support new devices or varying network requirements a standard
configuration is used for the radios and the following two key serial data parameters are adjusted:
•
Inter-Frame Gap (IFG)
–
used to detect new packets on the serial input to the radio
•
Maximum Transmission Unit (MTU)
–
used to define the over the air (OTA) packet size
To date, 4RF has lab tested and confirmed operation with the follow SEL Mirrored Bits® devices. Contact
4RF for preferred configuration:
•
2411 PAC (Programmable Automation Controller)
•
2505 series remote I/O modules
•
321 series relays
4RF is working with customers to confirm support for other devices as they are identified. The remainder of
this document details the configuration settings and general process to optimize the radio to support
additional devices, in addition to listing expected latencies under different configurations.
General Configuration
The configurations and process are aligned with a 2505 series remote I/O module device with serial baud
rate of 9600. As a ‘fast’
Mirrored Bits® device it is considered a good start point for optimization. For other
baud rates please refer to the table in Initial Setup for Mirrored Bits® Support on page 136 for initial MTU
and IFG settings.
The following are the recommended RF configurations and serial data configuration settings and to optimize
the performance over Aprisa SRi radios.
Recommended RF configurations are:
•
Radio > Channel Setup > Serial Data Stream Mode
to ‘Segregate’
•
Radio > Channel Setup > Network Traffic Type
to ‘
Serial Only
’
•
Radio > Radio Setup > Modulation
–
64QAM (low gain)