Comtrol DeviceMaster DM-2000 Series Installation And Configuration Manual page 150

Troubleshooting and Technical Support
General Condition
DeviceMaster continuously
reboots when connected to
some Ethernet switches
with the NS-Link driver
DeviceMaster continuously
reboots when connected to
some Ethernet switches or
routers
150 - Troubleshooting and Technical Support
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 driver 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
DeviceMaster.
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 DeviceMaster reboots. Therefore, the ID
query is not received by the DeviceMaster 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.
Explanation/Action
DeviceMaster Installation and Configuration Guide: 2000594 Rev. F