TC620-PID
Page 110
Note on Data Transfer Optimisation:
A 'word time' is the transmit time for one data word. The
amount of time one data word takes to travel on the line is determined by bit rate and word
length. Using the
UART gap timeou
t and
UART max. latency
variables you can tailor the data
channel for your specific protocol. A delay < 5 milliseconds is possible with minimal settings.
One or more data words are bundled in packets. The packaging process influences the
performance of the UART mode. At high bit rates, say 115 kbit/s, it may be desirable to adjust
some of the low-level UART settings to prevent high CPU loads. At such speeds, a large number
of small network packets might increase CPU load by 15%.
The process can be optimised using the RS-4xx settings in the Advanced Settings section.
Packets can be sent depending on the configuration of the
UART gap timeout
and
UART max.
latency
variables. These can be set such that fewer but larger packets are sent, making the
stream simpler to handle, at a considerably lower CPU load. Configuring these settings is often a
trade-off between latency (due to packaging) and payload efficiency. In other words, many
network packets with a small payload (low latency) versus fewer packets with a large payload
(higher latency).
At lower bit rates, a need for smoother PTZ may also require modification of these low-level
settings. Note that this depends on the application. For example, PTZ commands must be sent
frequently, but require few words. Latency can be minimised by proper fine-tuning of the
UART
gap timeout
and
UART max. latency
variables.
14.5.2
Transmitter #
Data RS-422/485 > Advanced > Transmitter 1
Item
Description
Connection priority
Parameter intended for use with MX Software Development Kit (MX SDK).
Multicast TTL
Range: [0...127]. Specify the number of routers (hops) that multicast traffic is
permitted to pass through before expiring on the network.
FloodGuard enable
Should be on when sending to a unicast IP address, so that an alarm can be
generated if no control messages from the receiver have come in for the time set
by the FloodGuard throttle delay variable.
FloodGuard throttle delay Amount of time after which the transmitter will enter throttled mode.
FloodGuard throttle
interval
Sets the frequency of empty packets being sent into the network while the
transmitter is in throttled mode.
Stream type
The UDP + NKF option will add an extended RTP header for Siqura applications
requiring extra information.
Link loss alarm timeout
Range: [1...1000] s. Default: 10 s. Time in seconds before alarm sent.
