I am having an issue with Centos 6 and an external USRobotics modem. We use the modem as part of a last resort SMS paging system.
Across multiple Dell servers, different models, I can't not get the modem to respond to simple AT commands while using Minicom. At the same time if I connect the server to a console port on a switch I can successfully access the switches serial console. So I know the serial port itself is working. The modem still works fine if connected to a Centos 5 server.
Any thoughts?
Graham Johnston
Network Planner Westman Communications Group 204.717.2829
johnstong@westmancom.com mailto:johnstong@westmancom.com
P think green; don't print this email.
On Mon, Sep 26, 2011, Graham Johnston wrote:
I am having an issue with Centos 6 and an external USRobotics modem. We use the modem as part of a last resort SMS paging system.
Across multiple Dell servers, different models, I can't not get the modem to respond to simple AT commands while using Minicom. At the same time if I connect the server to a console port on a switch I can successfully access the switches serial console. So I know the serial port itself is working. The modem still works fine if connected to a Centos 5 server.
Any thoughts?
Which device are you using for the serial connection. It should be /dev/ttyS0 or similar to provide the correct modem control signals. The modem probably won't respond unless the DTR (Data Terminal Ready) line is up. It's been quite a while since I had to look at the modems on our system that runs HylaFAX and dialup connections,
Bill
yeah, ttyS0.
Graham Johnston Network Planner Westman Communications Group 204.717.2829 johnstong@westmancom.com
think green; don't print this email.
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Bill Campbell Sent: Monday, September 26, 2011 12:14 PM To: centos@centos.org Subject: Re: [CentOS] External Dial-up Modem
On Mon, Sep 26, 2011, Graham Johnston wrote:
I am having an issue with Centos 6 and an external USRobotics modem. We use the modem as part of a last resort SMS paging system.
Across multiple Dell servers, different models, I can't not get the modem to respond to simple AT commands while using Minicom. At the same time if I connect the server to a console port on a switch I can successfully access the switches serial console. So I know the serial port itself is working. The modem still works fine if connected to a Centos 5 server.
Any thoughts?
Which device are you using for the serial connection. It should be /dev/ttyS0 or similar to provide the correct modem control signals. The modem probably won't respond unless the DTR (Data Terminal Ready) line is up. It's been quite a while since I had to look at the modems on our system that runs HylaFAX and dialup connections,
Bill
Graham Johnston wrote:
I am having an issue with Centos 6 and an external USRobotics modem. We use the modem as part of a last resort SMS paging system.
Across multiple Dell servers, different models, I can't not get the modem to respond to simple AT commands while using Minicom. At the same time if I connect the server to a console port on a switch I can successfully access the switches serial console. So I know the serial port itself is working. The modem still works fine if connected to a Centos 5 server.
I'd think that there may be some default settings in minicom that need to be different for that specific modem.
mark
On Mon, Sep 26, 2011 at 11:20 AM, Graham Johnston johnstong@westmancom.com wrote:
I am having an issue with Centos 6 and an external USRobotics modem. We use the modem as part of a last resort SMS paging system.
Across multiple Dell servers, different models, I can't not get the modem to respond to simple AT commands while using Minicom. At the same time if I connect the server to a console port on a switch I can successfully access the switches serial console. So I know the serial port itself is working. The modem still works fine if connected to a Centos 5 server.
I normally use ckermit (available from epel) for serial port access because you can 'set carrier off' before connect so it doesn't hang waiting for the carrier detect line to come up and because it has a scripting language that works the same over tcp (handy if you move your modems to a terminal server). I assume you know that the cable needs to be different for modem and console connections. You might also loop DTR to DCD, but then you won't know when the connections drop.
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