Eloquence - Frequently Asked Questions

SUPPORT - FAQs
Sprint 2, Elan, Elan Junior

Time Division Multiplexer Frequently Asked Questions

How do I connect my equipment to the high speed channel (HSC) on my Elan/Sprint 2 ?

Assuming its an X.21/V.11 HSC, for both the Elan and the Elan Junior, look in the manual Appendix K - HSC straight cables. This details the cable specification to connect to other equipment.
For the Sprint 2, either use the connector specification in the manual, or use specification below.
CABLE SPEC TO CONNECT TO A 15-WAY DTE PORT

25 WAY MALE D-TYPE 15 WAY MALE D-TYPE SIGNAL

4 6 CLKa

15 13 CLKb

20 4 RXDa

3 11 RXDb

8 2 TXDa

2 9 TXDb

24 5 INDa

7 12 INDb

7 8 SIG GND

Why do I occasionally get async errors on my TDM ?

When using a TDM to send Async data, there is no error correction on anything sent, so if there are errors on the digital service errors will occur on the multiplexers.
If data is very critical, then an error-correcting statistical multiplexer such as the Esprit should be used to ensure all data arrives correctly.
Problems with Continuous Asynchronous Data
A problem can occur if a TDM is being used to transport continuous async data due to independent clock references being used within connected equipment. Eloquence TDM multiplexers use a divisor of the composite LINK clock to produce exactly the baud rate required (referenced to the link clock) and uses this to output all the characters sent over the link.
If a TDM multiplexer is being sent continuous async characters at a slightly faster baud rate (perfectly possible, as all async devices use their own clock which is not referenced to anything else and will be either slightly faster or slower than nominal), then all the characters will be sent across the link perfectly, but they will be arriving at the remote multiplexer SLIGHTLY FASTER than they are being output. Eventually, the buffers at the remote site will overflow, and errors will occur.
This will, of course, even occur when the remote location has a loopback connector fitted to it, or when it is set to loopback. It is simply a regularly observed effect of async data when continuous characters are sent (RS232/V.24/ASYNC was never designed/intended to support continuous data).
If any gaps occur in the data flow (which is a natural requirement of async transmission), the buffers will empty out during these gaps, so overflow will never occur.

I'm getting data errors, how can I tell if it is the multiplexer or the line that's responsible ?

The best way is by using a data tester:
First run the tester into a data port that is set to loop.
Secondly try with the multiplexer in local composite loop.
Next set the Kilostream NTU (or whatever service you are connected to) to local loop.
Then check with the Kilostream NTU in remote loop.
Finally, test the setup with the remote data channel in loop.
This allows you to find where the errors are being introduced. For example, if there are errors between the data tester and the data channel in loop, there must be a problem either with the setup or the multiplexer - as the Kilostream is not being used.