Comtrol DeviceMaster AIR User Manual page 69

Troubleshooting and Technical Support
General Condition
DeviceMaster AIR
continuously reboots
when connected to some
Ethernet switches
DeviceMaster AIR
continuously reboots
when connected to some
Ethernet switches or
routers
Explanation/Action
The problem is caused by a L2 bridging feature called
Spanning Tree Algorithm (STA) in the Switch. This
feature is enabled by default in some switches. This
features causes time-out problems on certain L2
protocols, such as our MAC mode.
Resolution: There will be no firmware fix for this
problem. Only one of the following fixes is required for
resolution.
1. Disable STA in the switch.
2. Enable STA fast forwarding on the port.
3. Change the STA Forward Delay and Message Age to
minimum time values.
4. On the device, set the time-out value to 0 (to disable
loading of SocketServer) or 120. The command from
the redboot prompt is "Timeout 120" without the
quotes.
Problem Details: STA by default blocks packets for 30
seconds after an ethernet port auto negotiates. Blocking
of these packets causes the NS-Link driver load process
to fail.
The normal NS-Link load process is:
1. If NS-Link determines that it needs to load a device,
it resets the device. It does this to get the device into
Redboot mode. Only Redboot accepts "load binary"
commands, which are needed to load the NS-Link
binary into the device.
2. After a 6 second delay, NS-Link sends an ID query to
the device. This query is to verify that the device is in
Redboot and can accept "load binary" commands.
3. The device sends an ID query response.
4. NS-Link loads the device.
If the device is not loaded after "timeout" seconds
(default 15) , it loads SocketServer.
The above process fails when STA is running because the
switch blocks packets for 30 seconds after the RTS is
rebooted. Therefore, the ID query is not received by the
RTS and after 15 seconds the device loads SocketServer.
After 30 seconds, NS-Link finally can do an ID query,
which reveals that the device is not in Redboot. NS-Link
therefore reboots the device, and the process repeats.
Invalid IP information may also cause the switch or
router to check for a gateway address. Lack of a gateway
address is a common cause.
DeviceMaster AIR User Guide: 2000365 Rev. C - 69
General Troubleshooting