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Troubleshooting FIB1-E1/T1 |
This little guide will help to confirm if the FIB1-E1/T1 units are working normally. Then there are some hints on connecting the pair into a T1 link.
1. Below is a photo showing the factory PCb jumpers as they should be set for T1 operation. We use a common PCBA that can support both American T1 and European E1. For T1(DS1) please make sure that your units have R46 open and R47 shorted.
2. Test the units individually for link indication. Make sure the front panel DIP switches are all OFF.
A. T1; make a loop back plug using an RJ45 connector plug. Have one wire pair go from pins 1&2 and loop to pins 4&5. To maintain polarity, have pin 1 looped to pin 4 and pin 2 looped to pin 5. Apply power to the FIB1 converter. Insert the loop back plug into the T1 RJ45 jack. The LEDs for Power and T1 link should be on. Removing the loop back should make the T1 link LED go off. If this passes, the chances are very good that the T1 circuits are OK.
B. FX; To test the fiber port you will need a simplex single mode patch cable with SC at each end (or whatever cable type and connector for your unit). Apply power to the FIB1 converter. Create a fiber loop back using the simplex patch cable, connecting the transceivers Tx back to its Rx. Do not worry about the need for attenuators; none are required for the 15KM transceiver. Both the Power and Fiber Link LEDs should be lit. You can break and make the loop back and the LED indicator should follow the link status. Again, if this passes, the fiber transceiver is definitely good.
If both A and B tests pass, the converters are ready to apply in your circuit.
3. Please be aware that the RJ-45 connector follows USOC RJ-48C standard wiring for a terminating unit. This means, you may attach directly with a 1:1 connection to the service provider's line. The terminating unit receives signal on the pins 1&2 and transmits signal on pairs 4&5. When inserting the FIB1 pair in a T1 link, you will need a crossover towards your equipment so that the transmit and receive signal direction is maintained. In a crossover cable, the pairs 1&2 and 4&5 are crossed.
4. Because the FIB1 is transparent, it does not care about framing. However, it does require the right line code setting. When the line code setting DIP switch (SW1) is off, the default setting, the unit is set for B8ZS line coding. This is the normal line coding for most T1/DS1 transmission. The other setting is for AMI (SW1 ON) but we doubt the carrier will be using AMI.
5. If the converters you have are for single mode fiber, it might be possible to operate a short distance over multi-mode fiber, but there is no guarantee. Multi-mode cable has very high dispersion. It is definitely for sure that multimode fiber converters cannot operate on single mode fiber, even at short distance.
6. Lastly, for troubleshooting; When the two converters are linked by fiber, both will indicate a good fiber link. The Fiber Link LED indicates that fiber signal is being received. If one converter has a good link but the other does not, it means it is not receiving any signal on the fiber. If we have already confirmed the units are good, then it must be a problem with the fiber cables or patch cables.
Since the FIB1 is a terminating unit, it should have a T1 link indication once attached directly to the carrier's line. As long as the carrier's line is terminated on their side, there will be T1 signal present. If you don't have T1 link when connecting to your equipment, it is probably because the signals did not get crossed over. You need to run pair 1&2 at one end to Pair 4&5 on the other end and vice versa, between the FIB1 and your equipment.
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