VBAI GigE and Modbus must use common NIC?

[Johan]

Hi,

I cannot find any way to use separate NIC for GigE and Modbus TCP/IP in VBAI. VBAI insists on using wich ever adapter the GigE camera is using.

Any one that can help me?

[ChristopheC]

Hi,

Doesn't it work if you connect your modbus master device to a different adapter than the camera?

Can you describe a little better what you're experiencing?

Thanks,

Christophe?

[Johan]

Ok, I have 2 Ethernet boards installed my computer. The first one is for GigE communication to the camera, and the second one is for general purpose.

My first adapter should be dedicated to GigE to avoid interference when polling the modbus device.

I am interested in how to set up the second adapter to handle the mobus communication. I can only get modbus working if I use the same adapter as GigE.

Where do I find the option to select a specific NIC for handling Modus TCP/IP?

[BlueCheese]

Johan,

I believe the current Modbus server implementation binds to all local IP addresses (in the sockets world, this is equivalent to binding to INADDR_ANY or "0" in the LabVIEW TCP VIs). This means that you should be getting the behavior you want. You can verify this behavior by opening a command prompt on the machine running the Modbus server and typing "netstat -a -n | find "502" ". This should show a line like so:

TCP    0.0.0.0:502            0.0.0.0:0              LISTENING

This shows the sevrer is not bound to any specific local address on the TCP port 502 that is being used by the Modbus server. It will accept connections from any remote system connects via any working network interface on the system.

What is the nature of the problem you are seeing? Are you sure your networking topology and IP settings on the computers involved are correct? Is there a chance there is some sort of firewall that is blocking traffic to one of your network interfaces? Can you attach a copy of the output of "route print" on machines involved?

-Eric

[joshvm00]

I know this post is old but,

I have seen this same thing using VBAI 2010. I have found that disabling my GigE NIC forces VBAI to switch to the NIC that I want it to reference, but if I restart the program, it automatically selects the GigE NIC and I can't read/write to Modbus registers and my modbus master software displays a no-connection error. 

Also, I have been trying to communicate with the VBAI modbus slave with a Modbus Master device configuration software on a different computer and haven't been able to get it working properly. After reading this post, I tried typing "netstat -a -n" in command prompt and couldn't find any reference to port 502 (I am expecting "TCP    0.0.0.0:502            0.0.0.0:0              LISTENING"). Please advise, Thanks!

[joshvm00]

EDIT: Here is what I see. Note that this is what I see from the computer running my Modbus Master server. The computer that is running VBAI has IP Address 192.168.0.110. I see a ton of reference to this IP under the Foreign Address column, but the status is FIN_WAIT_2 (I don't know what this means). My other Modbus devices work properly and use IP addresses 192.168.0.1, 192.168.0.2, etc.

Proto Local Address Foreign AddressState
TCP 0.0.0.0:135 0.0.0.0:0 LISTENING
TCP 0.0.0.0:445 0.0.0.0:0 LISTENING
TCP 0.0.0.0:3389 0.0.0.0:0 LISTENING
TCP 0.0.0.0:5800 0.0.0.0:0 LISTENING
TCP 0.0.0.0:5900 0.0.0.0:0 LISTENING
TCP 127.0.0.1:1048 0.0.0.0:0 LISTENING
TCP 127.0.0.1:1171 127.0.0.1:1172 ESTABLISHED
TCP 127.0.0.1:1172 127.0.0.1:1171 ESTABLISHED
TCP 127.0.0.1:1173 127.0.0.1:1174 ESTABLISHED
TCP 127.0.0.1:1174 127.0.0.1:1173 ESTABLISHED
TCP 127.0.0.1:5152 0.0.0.0:0 LISTENING
TCP 127.0.0.1:5152 127.0.0.1:2703 CLOSE_WAIT
TCP 172.16.3.87:139 0.0.0.0:0 LISTENING
TCP 172.16.3.87:2906 74.125.225.149:443 TIME_WAIT
TCP 172.16.3.87:2997 74.125.225.149:443 ESTABLISHED
TCP 172.16.3.87:3016 208.85.40.20:80 TIME_WAIT
TCP 172.16.3.87:3033 74.125.225.149:443 ESTABLISHED
TCP 172.16.3.87:3034 8.27.81.126:80 CLOSE_WAIT
TCP 192.168.0.254:139 0.0.0.0:0 LISTENING
TCP 192.168.0.254:2910 192.168.0.1:502 ESTABLISHED
TCP 192.168.0.254:2911 192.168.0.2:502 ESTABLISHED
TCP 192.168.0.254:2912 192.168.0.4:502 ESTABLISHED
TCP 192.168.0.254:2913 192.168.0.9:502 ESTABLISHED
TCP 192.168.0.254:2915 192.168.0.200:502 ESTABLISHED
TCP 192.168.0.254:2999 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3001 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3002 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3003 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3004 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3005 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3006 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3007 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3008 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3009 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3010 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3011 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3012 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3013 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3014 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3015 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3017 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3018 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3020 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3021 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3022 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3023 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3024 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3025 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3026 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3027 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3028 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3029 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3030 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3031 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3032 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3035 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3036 192.168.0.110:502 FIN_WAIT_2
TCP 192.168.0.254:3037 192.168.0.110:502 ESTABLISHED
UDP 0.0.0.0:445 *:*
UDP 0.0.0.0:500 *:*
UDP 0.0.0.0:4500 *:*
UDP 127.0.0.1:123 *:*
UDP 127.0.0.1:1025 *:*
UDP 127.0.0.1:1049 *:*
UDP 127.0.0.1:1072 *:*
UDP 127.0.0.1:1154 *:*
UDP 127.0.0.1:1900 *:*
UDP 127.0.0.1:2637 *:*
UDP 172.16.3.87:123 *:*
UDP 172.16.3.87:137 *:*
UDP 172.16.3.87:138 *:*
UDP 172.16.3.87:1900 *:*
UDP 192.168.0.254:123 *:*
UDP 192.168.0.254:137 *:*
UDP 192.168.0.254:138 *:*
UDP 192.168.0.254:1900 *:*