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Why Crestron can use USB to RS232 adapter for programmatically control SX20 but notebook cannot?


Why Crestron can use USB to RS232 adapter for programmatically control SX20 but have com port notebook cannot(use Putty and hypertrm)?

I try speed 9600,38400,115200,but Putty and hypertrm is no report and cannot enter the function key .

Can i use USB to RS232 adapter connect SX20 like MXP? have any questions is the need to pay attention to it?

Cisco Employee

Is this a document or a question? When using a USB to DB-9 cable, the DB-9 async connection presents itself as a DTE.

If you take your notebook and another USB to DB-9 cable, that will be a DTE too. To connect both, you would need a null-modem or a cable which presents itself as a DCE. I assume the cabling you have to connect the Crestron has the appropriate layout, whilst your notebook does not.


Dear Danny

Thank you for your reply

So how can i do to use USB to RS232 control the SX20 like laptop connected USB to RS232 adapter to control as MXP ?(same setting,not telnet)

Cisco Employee

So you have a laptop with some cable which hooks up to the MXP and can control the latter? When I look at the following manual I see that this type of MXP has a DB9 female port named data 1 and data 2. Does your MPX also have a female DB9 connector? That kind of interface is a DCE. If you use this same cable from your laptop combined with a USB to DB9 cable on SX20, you would have 2 DTEs connecting to eachother. That does not work. So you need a null-modem for DB9 in-between.

And on SX20 use something like this :
Then you would have DTE from SX20, DTE from your laptop with DB9 male connectors, and then you put in the null-modem cable which has 2 female DB9s.

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