It shows success:

```
msf auxiliary(modbusclient) > run

[*] Sending READ COIL...
[+] Coil value at address 0 : 2
[*] Auxiliary module execution completed
```

Even when wireshark says the response in an error one:

```
function 1:  Read coils.  Exception: Illegal data address
exception code: Illegal data address (2)
```

Maybe the response parsing isn't accurate enough?