Troubleshooting (Auto-Discovery Mode)

Top  Previous  Next

 

This topic provides a list of hints that can help you figure out why you cannot "find" your Device Server in the device list of the DS Manager or why the DS is shown as having an unreachable IP-address (status icon is "grayed"). The topic only covers the auto-discovery access mode. See troubleshooting (address book mode) and troubleshooting (COM mode) for hints on other two access modes.

 

Here is why you may not be able to see the DS in the device list:

 

The DS may be switched off or not connected to the network*.

 

The DS may not be on the local network segment. In the auto-discovery access mode the DS Manager can only "see" Device Servers on the same network segment as your PC (local Device Servers). Remote Device Servers located behind routers (firewalls, etc.) cannot be accessed. Use address book access mode to work with remote Device Servers.

 

Firewall software on your PC may be preventing communications between the DS Manager and Device Servers. This communications relies on UDP traffic between port 65534 of the PC and port 65535 of the Device Servers. Make sure that your firewall software does not ban this traffic! Our experience shows that many Users are not aware of the firewall software installed on their own PCs! Some firewalls come as part of larger "protection" suites (anti-virus, anti-intrusion, etc. programs). Some operating systems, such as Windows XP, include the firewall software too!

 

If your DS is running an older firmware (V2.xx) then it will not be accessible through the network and visible to the DS Manager in the following cases:

 

 

LED_ser_progWhen the DS is in the serial programming mode (status LEDs of the DS "play" the pattern as shown on the left)**;

 

 

LED_error_modeWhen the DS is in the error mode (status LEDs of the DS "play" the pattern as shown on the left)**.

 

This does not apply to the Device Servers running DS firmware V3.xx or higher. In this firware the DS is visible on the network at all times.

 

If there are many devices shown in the device list the DS you are looking for may actually be in the list! A very useful buzz feature allows you to match device list entries to their actual physical Device Servers. Use this function and you will probably "find" your DS (buzz feature is only supported by DS firmware V3.xx or higher).

 

Here is why the DS may be shown in the device list as having an unreachable IP-address:

 

Because the IP-address of the DS is really unreachable. This means that it is outside of the IP-address range defined for the subnet to which your PC is connected. For example, if the IP-address of your PC is 192.168.100.30 and the netmask is 255.255.255.0 then your local subnet has the IP-address range from 192.168.100.1 to 192.168.100.254***. So, if you connect the DS to the local network segment and set its IP-address to 192.168.100.40 then the DS Manager will be able to access this DS. If you set the IP-address to 192.168.10.40 then your PC will decide that this IP-address is on some other subnet and will relate all communications (related to this IP) to the "default gateway". This means that network packets addressing this DS won't even be released into the network to which the DS is physically connected.

 

Because the DS Manager has cached a different MAC-address for the IP-address currently assigned to the DS in question. This can happen if you connect different Device Servers one by one to the same network segment and then assign the same IP-address to each Device Server. This is often reported by our Users that want to pre-program or test several Device Servers. What happens here is that after the first DS is detected/accessed by the DS Manager the PC finds out the MAC-address that corresponds to the IP-address of the DS****. If you quickly connect another DS in place of the first one and assign the same IP-address to it the PC won't bother to "resolve" the IP-address again and will attempt to communicate with the "cached" MAC-address instead. Since MACs are unique for each DS the DS Manager won't be able to communicate with the new DS using "normal" IP-addressing. This problem will be resolved automatically after IP-MAC mapping data kept by the PC expires (about 20 minutes later). If your task is to pre-program/test several Device Servers then you don't have to wait until this happens- the DS Manager automatically chooses broadcast access for Device Servers that (temporarily) cannot be addressed using their IP-address.

 

Because the IP-address of the DS is the same as the IP-address of some other device on the network segment. The best way to find out if this is so is to switch the DS off and try to PING the IP-address in question. If you still get PING replies then this means there is some other network device that is using this IP!

 

Because of the firewall software installed on your PC. We have seen cases when the DS Manager could discover the Device Servers (broadcast UDP communications to port 65535 were allowed) but could not address these devices using normal IP addressing (non-broadcast UDP communications to port 65535 were blocked). When this is the cause of the problem all of your devices will be seen in the DS Manager with grayed icons.

 

* Really sorry for this "hint"... it's just that this is the root cause of many problems!

 

** See status LED signals for the full list of all available patterns.

 

*** .0 and .255 are not allowed in principle.

 

**** MAC-address is an actual physical network address used by all Ethernet devices. When connecting to the target device with a specified IP-address the "connectee" first finds out what MAC-address corresponds to the targeted IP-address. This way IP-addresses are mapped onto the MAC-addresses. This process is called "address resolution" and is performed using a special Address Resolution Protocol (ARP). Mapping information is memorized ("cached") by the PC and is remembered for about 20 minutes. The information is reused until it expires. This means that instead of using the ARP again the PC simply uses cached data instead.