Tibbo Device Servers ("DS") feature two status LEDs*- Status Red (SR) and Status Green (SG)- that display various states of device operation. DS states are indicated by way of playing "LED patterns". Patterns in this topic are represented graphically in the following manner:
The pattern above means that both green and red status LEDs blink together three times. The following pattern means that red LED makes one long blink followed by two short ones:
Status LEDs of the DS display a number of conditions, some of which can exist at the same time. Because status LEDs can reflect only one condition at any given time there is a certain hierarchy that defines which conditions are more important and displayed in favor of other conditions.
Listed below are all patterns generated by this firmware**. Patterns are arranged in order of decreasing priority. For example, serial programming mode pattern is listed above the error mode pattern which means that if the DS is running in the serial programming mode and error mode at the same time it is the serial programming mode pattern that will be played by the status LEDs.
Most LED patterns correspond to states of various flags contained in response to the Echo (X) command . Where this is true a short note was added to reflect this fact (like this: s flag ='S').
Patterns that are played once in response to a certain event:
| Powerup pattern. This pattern is played once when the DS is switched on. |
 | Buzz pattern. Both LEDs blink fast- this pattern is played when the DS receives the Buzz (B) command. This is used to identify a particular DS. |
Patterns that are played repeatedly until replaced by another pattern:
| Ethernet port failure (e flag= 'N'). Indicates that the Ethernet port hardware is malfunctioning and network communications with the DS is not possible. |
 | IP-address not obtained (i flag= '*'). Occurs at startup when DHCP (DH) setting is 1 (enabled) and the DS has not yet obtained its IP-address from the DHCP server. |
[V3.54+]: PPPoE link is being established (details- p flag ). Occurs at startup when PPPoE Mode (PP) setting is 2 (on powerup).
 | [V3.54+]: PPPoE login failed (p flag= 'D'). Occurs at startup and means that either PPPoE login name and password (defined by PPPoE Login Name (PL) and PPPoE Login Password (PD)settings) are incorrect or PAP authentication protocol used by the DS is not supported by Access Concentrator. |
 | Data connection is closed (c flag= '*'). This pattern means that no data connection (TCP or UDP) with any network host is currently established so the DS is idle. |
 | Sending ARP (c flag= 'A'). Displayed when the DS is sending ARP requests to find out MAC-address of the destination network host with which the DS is about to establish a connection. |
[V3.54+]: PPPoE link is being established (p flag = 'B'). This happens when PPPoE Mode (PP) setting is 1 (on connection) and the DS needs to create a PPPoE link in order to connect to remote network host.
 | TCP connection is being opened (c flag= 'O'). Indicates that TCP connection (either incoming or outgoing) is being established (i.e. SYN-SYN-ACK exchange is in progress). |
 | TCP connection reset (rejected) by the network host (c flag= 'R'). Means that the TCP connection has been reset (using RST packet) by the network host to which the DS has tried to connect. |
 | Link Server login in progress (c flag= 'L'). Means that the DS has already established TCP connection to the Link Server and is now attempting to login. |
 | Link Server login failed (c flag= 'F'). Means that data connection to the Link Server could be established but the server has rejected this DS (because the data in the Owner Name (ON), Device Name (DN), or Password (PW)setting is incorrect or for some other reason). |
 | Data connection is established or being closed (c flag= 'U' or 'C'). Means that data UDP "connection"or TCP connection is currently established or that TCP connection is being closed (i.e. FIN-ACK-FIN-ACK exchange is in progress). |
When the data connection is established the following patterns are additionally displayed:
 | Data is being routed, no overruns detected (E flag= '*' and S flag= '*'). This pattern is played when the data connection is established and the data is being routed through the DS; |
 | Buffer overrun, no data routing (E flag= 'E' or S flag= 'S'). This pattern is displayed when the data connection is established and the routing buffer overrun has been detected (within the present data connection); |
 | Buffer overrun + data routing. Data routing and overrun can be displayed at the same time. |
* For modules such as EM100, EM120, EM200, EM203(A) there are two control lines to connect external status LEDs.
** Patterns related to the NetLoader and the Monitor are not shown here!
