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6193-3201
How a Link connection is lost
The RM-90 will reset the Link if:
… Excessive retries:
When a RM-90 unit transmit a wireless message to another unit, the destination unit
will transmit back an acknowledgment. If the source unit does not receive an acknowl-
edgment, it will re-send the message – this is known as a “re-try”. Both Access Point
and Client will drop the link if the number of retries for a single packet exceeds (7)
times. Packets are retransmitted according to an increasing time delay between retries,
with each attempt on a different frequency.
… Inactivity:
During periods of inactivity, Clients will periodically check that the link to the Access
Point remains intact. This process is called “reassociation”, and will occur approxi-
mately (6) beacon intervals after the last packet was sent to the Access Point. If a
Client unit does not get a response from its Access Point, it will retry the reassocia-
tion request (7) times before resetting the link. If an Access Point does not receive any
traffic from a Client, including reassociation requests, within (12) beacon intervals, the
Access Point will reset the link.
After a Client has reset it’s Link status, it will start scanning for an Access Point, as if it
has just started up.
LED Indication
The following table details the status of the indicating LEDs on the front panel under
normal
operating conditions.
LED Indicator
Condition
Meaning
OK GREEN
Normal
Operation
OK
RED
Supply voltage too low.
Radio RX
GREEN flash
Radio receiving data
Radio RX
RED flash
Weak radio signal
Radio TX
Flash
Radio Transmitting
Radio LINK
On
On when a radio communications link is established
Radio LINK
Off
Communications failure or radio link not established
Radio LINK
GREEN flash
RED flash
Serial Port Receiving
CTS low
LAN
ON
Link Established on Ethernet port
LAN
Flash
Activity on Ethernet port.
Serial
GREEN flash
RS-232 Serial Port Activity
Serial
RED flash
RS-485 Serial Port Activity
DIO
On
Digital Output ON
or
Input is grounded.
DIO
Off
Digital Output OFF
and
Input is open circuit.
The Ethernet RJ45 port incorporates two indication LEDs. The LINK LED comes on
when there is a connection on the Ethernet port, and will blink off briefly when activity is
detected on the Ethernet Port. The 100MB LED indicates that the connection is at
100 MBit/Sec. The 100MB LED will be off for 10MB/Sec connection.
Other conditions indicating a fault are described in Chapter Six
Troubleshooting
.
