Experimental Physics and Industrial Control System
The default "TCP alive check time" value is 7 minutes and the default
"Max connection" is 1 for a moxa port configured as a TCP server. If a
client doesn't properly close the connection, the next client will have
to wait 7 minutes before it can successfully connect to the that port.
If the telnet connection from Windows was tested before the telnet
connection from Linux and the Windows telnet did not exit cleanly
(ctrl+c or closing the command window instead of typing "close" and
"quit"), the Linux telnet may actually succeed after the "TCP alive
check time" expires.
I've seen this problem with VMEs running VxWorks and my workaround was
to reduce the "TCP alive check time" to 1.
Kevin
On 1/24/17 7:33 AM, Mark Rivers wrote:
> I'm trying to help Sunny to connect from Linux to a serial port on a Moxa box. It is not working, and I am stumped, so any ideas are welcome.
>
>>From Windows he can telnet to it:
>
>> when I telnet from windows
>> telnet 192.168.127.254 4001
>> It prompts a blank screen and for other IP or ports like 192.168.127.254 5064, 192.168.127.34 4732 etc. it simply says host not available so I think port 4001 should be good.
>
> When he connects it to Linux he can ping it:
>
> ping 192.168.127.254
> PING 192.168.127.254 (192.168.127.254) 56(84) bytes of data.
> 64 bytes from 192.168.127.254<http://192.168.127.254>: icmp_seq=1 ttl=255 time=1.69 ms
> 64 bytes from 192.168.127.254<http://192.168.127.254>: icmp_seq=2 ttl=255 time=0.797 ms
> 64 bytes from 192.168.127.254<http://192.168.127.254>: icmp_seq=3 ttl=255 time=0.753 ms
>
> ifconfig looks OK:
> eth0 Link encap:Ethernet HWaddr D8:CB:8A:9C:61:96
> inet addr:192.168.127.0 Bcast:192.168.127.255 Mask:255.255.255.0
> inet6 addr: fe80::dacb:8aff:fe9c:6196/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:16 errors:0 dropped:0 overruns:0 frame:0
> TX packets:63 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:1454 (1.4 Kb) TX bytes:10799 (10.5 Kb)
>
> arp looks good:
> sbin/arp
>
> Address HWtype HWaddress Flags Mask Iface
> 10.128.0.254 ether 00:00:5e:00:01:83 C eth1
> 10.128.0.99 ether 00:04:96:6d:67:7f C eth1
> 10.128.0.253 ether 00:04:96:15:5e:70 C eth1
> 10.128.0.238 ether 00:04:96:27:50:63 C eth1
> 10.128.0.244 ether 00:04:96:34:ea:f2 C eth1
> 10.128.0.252 ether 00:04:96:28:24:ce C eth1
> 10.128.0.237 ether 00:04:96:51:a8:8b C eth1
> 192.168.127.254 ether 00:90:e8:4e:6e:4e C eth0
> 10.128.0.251 ether 00:04:96:16:c7:50 C eth1
> 10.128.0.249 ether 00:04:96:05:7a:13 C eth1
> 10.128.0.247 ether 00:04:96:36:54:da C eth1
> 10.128.0.246 ether 00:04:96:21:d6:10 C eth1
>
> The firewall is disabled:
> systemctl status SuSEfirewall2.service
>
> SuSEfirewall2 phase 2
> Loaded: loaded (/usr/lib/systemd/system/SuSEfirewall2.service; disabled)
> Active: inactive (dead)
>
> But when he tries to telnet from the Linux box it times out:
>
> telnet 192.168.127.254 4001
> Trying 192.168.127.254...
> telnet: connect to address 192.168.127.254<http://192.168.127.254>: Connection timed out
>
> Any ideas what could be causing this?
>
> Thanks,
> Mark
>
>
>
- References:
- problem connecting serial device with moxa 5150A Sunny Badkul
- RE: problem connecting serial device with moxa 5150A Mark Rivers
- RE: problem connecting serial device with moxa 5150A Mark Rivers
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