Media Access Control; Store And Forward Operation - GE MDS SD Series Technical Manual

Media Access Control

(AP menu shown)
• — Selects
Device Type
as the Controller of the RF network. Only one radio is configured as an AP. Typically
this is the "polling master." A Remote is connected to end devices in the field (e.g. PLC,
RTU), and there can be any number of these in a network. Each Remote must have a
unique Unit Address, which is set on the
tings" on Page 47). A Store and Forward device is a radio designated to retransmit data
to/from an outlying Remote (see
• — (AP Only) Selects whether or not a Store and Forward radio is present in
SAF Network
the network (
True
work beyond the primary "footprint" of the system. This can be used to link outlying
Remotes (or Remotes blocked by terrain or other obstructions) into the network. A de-
tailed discussion on using Store and Forward is provided below.
•
Repeater Network
repeater station, or communications will not work. Remotes automatically learn this set-
ting from the AP.
•
Tail End Network
End Link network and the user wishes to send DLINK messages i.e. PulseNET network
monitoring to the entire network operating in Packet w/MAC mode.
• — If a message is not acknowledged after transmission it will be resent. This
Retry Count
value controls how many times the radio attempts to resend the message before discard-
ing it.
•
Time-to-Live (s)
stamped and queued for radio transmission. If the radio cannot transmit the message be-
fore the Time-to-Live (TTL) value, the message is discarded. This helps prevent stale or
old data from being sent over the air.

Store and Forward Operation

Store and Forward (SAF) operation extends a wireless network's coverage area by electing a de-
vice (or devices) to store data and forward it to a unit (or units) beyond the reach of the primary
coverage area. Conventional RF repeaters receive and transmit data simultaneously. They are
effective at increasing range with low latency, but they are more expensive, have high power
consumption, and require more complex installation. SAF-designated units act as smart single
radio packet repeaters. The SAF feature provides a simple, low cost alternative to range exten-
sion when a traditional repeater isn't desired.
MDS 05-4864A01, Rev. I
,
Access Point Remote
SAF Network
), or not ( ). Store and Forward extends the coverage area of a net-
False
— (AP Only) This setting must be enabled if the RF network contains a
— (AP Only) This setting must be enabled if the network contains a Tail
— When a message arrives from the payload interface(s) it is time-
SD Series Technical Manual
, or
Store and Forward
screen (see "Diagnostic Set-
Diagnostic Settings
, below).
. An Access Point serves
45