How to connect a slave using modbus poll modbus slave

hay I installed modbus poll with a simple configuration

my network :
my ip address :

i have one slave
i use modbus slave here is my configuration

the network of my slave is :
the ip address of the slave is :

the ping goes between the master and the slave

but when i try to connect i have this error

can anyone help me

Why are you using port 80 instead of the default 502?

1 Like

it doesn’t change anything I think

do you have any idea where the problem is ??? I have disabled my firewall too

No I don’t know what’s wrong. The port looks wrong to me. But I don’t know how your simulator is set up.

I changed the port
port 502

but i still have the same issue

I have to find a solution

Your client’s “Remote Modbus Server” should point at the slave’s IP address.

1 Like

I thought we could put the master and the slave in two different networks

So if I understood correctly the address of the master must be the same for the slave

No. The master keeps his own address. But the master needs the slaves address so it knows where to go to make the connection. The slave doesn’t need to know the master’s address, because the slave is just listening for a connection (from anywhere, usually). The slave just needs to know what address of his own to use for listening (since computers can have multiple networks and addresses).

i did exactly what you said but i still have the same problem is there an option in modbus pool to specify the ip address of the slave and the master

I looked everywhere but I can’t find a solution

as you can see the IP address of the master is the same as the IP of the slave but it doesn’t work

Looks right. I don’t know what the problem is. If it is still the same error, then it is probably either another firewall or some other network misconfiguration.

First you were at 192.168.254, in your recent image you were at 192.168.112

Run an ipconfig in CMD on your PC/Server with Modpoll and post the screenshot

Pssst! Read the whole thread… The OP wants master and slave in different nets.