Serial/Null Modem notes
A very interesting list of notes about serial connections. This reminded me of the Lantronix issue I dealt with a few months back in which the Lantronix would literally begin to crawl when hooked up to a Nortel (I think it was a Nortel) phone switch: Plug in the phone switch, Lantronix crawls; remove phone switch, Lantronix returns to normal. Literally NO setting I could put in place would correct this. This link gave me some new ideas that didn't pop up at the time.
Slight edit: This link shows a nice option for making null modem adapters with RJ45-to-DB9 adapters. I really want to try this out now.
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I noticed your posting and I am concerned you are having issue with a Lantronix product. Your explanation needs more details to evaluate your issue.
ReplyDeletePlease contact Lantronix Tech Support and ask for the Tech Support Supervisor for more assistance. We want all our customers to have a positive experience with Lantronix solutions.
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Lan and Gary,
ReplyDeleteSince I am not currently at work I can't give you the specifics (code rev, etc) but...the Lantronix was connecting to the serial port of a Nortel phone switch (unsure of the model) for management. When it was connected to the Lantronix and any attempt was made to connect via the port, the Lantronix would slow to almost unusable levels. Trying to break out of the port connection would take in the neighborhood of 2-3 minutes sometimes. If the phone switch was removed, the Lantronix went back to normal. As I recall, this was with an SLC 32 or 48. I upgraded the code (we were one rev behind the most current) and tweak the port settings a helf dozen ways but to no avail. The same connection, when run to a Windows laptop, worked perfectly. I brought the links in this post to the attention of the phone switch admin hoping he'd want to explore the issue further but he informed me the the switch was slated for replacement and the issue pretty much died there.
I can say that of every other device (a few hundred) connected to a few dozen Lantronix devices, we have never seen this issue. It must be some signal (DTR/DSR, RTS/CTS, etc) that the phone switch is sending...or a voltage issue. But no one was/is sure. I was curious if the high speed vs low speed serial info listed in the link might have helped isolate the problem.