Laptop network issues

[dr pepper]

If I plug a ethernet device (modnus gateway etc) into my works laptop I can use it no problem, also if I plug the same device into my router at home it works.
However while at home plugging the network device into my laptop does not work.
I have dhcp disabled, networking trouble shooter says the device doesnt have an IP, assigning an IP on the same subnet as my laptop doesnt seem to work either.
Can I sort this out, or do I need a really long ethernet cable.

 

[FvM]

Your report is inaccurate. What do you mean with the "subnet of your laptop". Have you connected your notebook to router through Wifi and received an IP address? The notebook's ethernet port does not necessarily share the same subnet, it must be explicitely assigned an IP address through network setup. Excecute ifconfig from command shell to see the actual assignments.

 

[KlausST]

Hi,
it should be ne security issue if you report your
* devices IP addresses (notebook, router...)
* and the according subnet masks

check whether there are different values for WiFI and LAN .. in case both are activated at the same time.

Klaus

 

[danadakk]

1) Laptop 10/100/1000 port enabled ?
2) Port has DHCP enabled on it
3) Run ipconfig (not ifconfig) in Windows CMD window to see whats assigned to it


Regards, Dana.

 

[dr pepper]

Its 10/100.
DHCP disabled on the gateway.
However ipconfig reports an autoconfig IP plugging in the gateway, changing the mac of the gateway changes the autoconfig IP.
Pinging this IP does come back with a reply.
So dhcp is assigning new IP's, so is not disabled.
Running IP scan before & after plugging in the gateway doesnt show extra IP's, so theres some kind of conflict.

 

[KlausST]

Hi,

there may be more than one DHCP in a network...

use a network sniffer to know what´s going on.

Klaus

 

[FvM]

Sounds confused. Simply assign fixed IP address to notebook ethernet port and fixed address of same subnet to the gateway.

 

[dr pepper]

I'm not an expert on networks so I might be upside down on this to an extent.
Everyone starts from the beginning.
I'll try assigning the IP's and see what happens.

--- Updated Aug 14, 2021 ---

Tried going into adaptor options & setting the IP to 192.168.0.10, I now get a return on a ping to that address, however the gateways setup page on default port 80 does not work using a browser.
It does work if I plug the gateway into the router.

 

[FvM]

What does this mean? The gateway does either use DHCP by default, so it will obtain an IP in the subnet of the router. You can achieve a similar behaviour by running a DHCP server on the notebook. Or it has a default fixed IP after factory reset, in this case you have to assign suitable IP parameters to the ethernet port of your notebook, or an additional route to the gateway IP.

--- Updated Aug 14, 2021 ---

Can you post the gateway brand and type? If the web access ist done by device name, it depends on a DHCP server with host name resolution.

 

[dr pepper]

The gateway has a Dhcp tickbox, but its greyed out, must be a cheaper version.
I read to connect a device without a router I either need a software driver or a crossover cable, I have the gear to do the latter.

 

[FvM]

I claim that any network device on the market can be configured and operated using a peer- to- peer connection with a windows or linux computer. Crossover cable is required with older computers that don't implement auto-X-over (most 10/100 only ethernet ports).

 

[dr pepper]

No argument, I'm the inexperienced one.
Well maybe not so bad.
I setup the modbusRTU/modbustcp gateway with it plugged into my home router where I'm able to access its setup screen using a browser, then tried using it with the laptop running HMI software that tries to communicate to a modbusRTU device over the ethernet.
And it works, must be a browser thing, comms over modbus port 502 still works.
ModbusRTU communicates over RS232 or RS485 whereas modbusTCP uses ethernet.
I assume the software using port 80 & port 502 as well as UDp and TCP protocols is why it only works plugged into the router.