Hello,
I would like to connect a Fastrack Xtend GPRS modem to the RS232 port of a CR1000.
Before doing this test, I made a connection test with the same modem to the CS I/O port of the same CR1000 and it worked. I used a SC932A device to connect the modem to the CR1000. I could get an IP adress and transfer data using FTPClient.
Now, I would like to do the same but using the RS232 port of the CR1000 and I face troubles.
The connection is made as followed:
Fastrack Xtend GPRS modem connected to the CR1000 via the RS232 port with a gender changer. Previously, the modem configuration has been set to 115 200 baud (AT+IPR=115200).
In device config utility, I changed the port configuration in "ComPorts settings" as follow:
- Select the Comport -> RS232
- Baud Rate -> 115.2K
The rest of the configuration of the CR1000 has not been changed and is the as when I connected th modem to the CS I/O port of the CR1000.
Does anybody have an idea on what can be wrong in my configuration?
Thanks,
Coralie
You need a male to male null modem not a 'gender changer'
Thanks for your quick reply!
Can you tell me why I should use a null modem instead of a gender changer? Why is it necessary to switch the transmit and receiver part when connect a modem to the RS232 port of a CR1000?
Coralie
RS232 connections are either DTE or DCE if you connect DTE (male) to a DCE (female) then a normal straight through serial cable can be used. If DTE to DTE then a female to female null modem is required and in this case DCE to DCE a male to male null modem is required. The reason is if you use a serial cable then the TX pin of the modem will be connected to the TX pin of the CR1000 and the same with the RX pin. Obviously it will not work.
Null modems cross over the TX and RX wires to the correct pins at both ends.