Modbus TCP/IP

cjjeeper · Dec 11, 2020

I have a Goulds water pump skid running the Xylem e-MT controller. This controller has a modbus TCP/IP interface.

I have configured the service screen for the IP that sets the modbus interface.

I cannot make a connection to it via Modscan32...I have tried all memory areas in the documentation and I cannot get a connection. Currently their tech support is not answering calls (for 2 days now).

Any help / experience on this?

[all I can do on the xylem side is set an IP address and reboot it. cannot check the port or anything else.]

Thanks in advance.

id10t_error · Dec 11, 2020

I like to use modpoll to test Modbus devices. Works well as I find the command line much easier. Also, try directly connecting the PC to the device to make sure it isn't the network. I like to use WireShark to verify the device's mac address and IP address.

EDIT: If the device does not block pings, you can use angryIP Scanner to find open ports on a device. nmap is awesome but a bit more complicated and has a windows version. The default modbus port is 502

widelto · Dec 11, 2020

@id10t_error: I like your avatar, I used to work with DEC Digital Equipment Corp back in the 80´s . VMS Vax management system was the OS at that time.

Ken Roach · Dec 11, 2020

Can you connect to it in any other way, like ordinary PING or a Web interface ?

Try also TCPING, which simply opens a TCP connection on a specific Port number. Port 502 is standard for Modbus/TCP, but sometimes folks use Port 503 and up.

https://www.elifulkerson.com/projects/tcping.php

Running Wireshark at the same time as you try those tools sometimes gives you insight into the device's basic connectivity as well.

id10t_error · Dec 11, 2020

@widelto Thanks. Big openVMS fan here. You can use SimH to run pdp-11 and vax. Or an Alpha with Alpha station

FYI,
VMS is porting OpenVMS to the Intel x86-x64 and I hope there is a come back as i just love that OS.

widelto · Dec 11, 2020

@id1ot_error: we used to have several pd11-44, Vax 750 and Vax 780, we have Decnet network thru microwaves, it was like 500 miles only on our caribbean coast.
We used to handle banks, and goverment offices in seven cities.
Thanks for the links.

cjjeeper · Dec 11, 2020

I can ping it. and I am direct connected PC to device

let me see if I can check the port....I of course assumed its 502

drbitboy · Dec 11, 2020

cjjeeper said:
I can ping it. and I am direct connected PC to device

let me see if I can check the port....I of course assumed its 502

Code:

% telnet <PLC_ip_address> 502

that always floated my boat.

cjjeeper · Dec 11, 2020

I used that AngryIP scanner and found that the open port is 80.....

So I can now connect but there are no addresses that don't give me a READ/WRTIE error....

Toine · Dec 11, 2020

Port 80 is the default port for http traffic. In other words: html web pages to be looked at by means of a web browser (Chrome, Firefox, Edge, Internet Explorer, Safari etc). It will not give you your modbus connection. But not all is lost - it is very likely that you will find a web server at port 80. Connect a laptop or desktop computer on the same network, with a fixed IP address in the same range as your device. Then point your web browser to the IP address of the device. See what comes up. You may find a web interface with configuration options and/or documentation of the device that you can access from your computer. Could be a starting point to work from.

Ken Moore · Dec 11, 2020

Many Modbus devices require you to enable modbus and set the port, when you set the IP. May be your issue.

BachPhi · Dec 12, 2020

widelto said:
@id1ot_error: we used to have several pd11-44, Vax 750 and Vax 780, we have Decnet network thru microwaves, it was like 500 miles only on our caribbean coast.
We used to handle banks, and goverment offices in seven cities.
Thanks for the links.

Adding 11/23 which looks like a desktop PC. Capable of boot and load whole OS via DECNET. The RC25 disk drives, the big tapes on 11/44.

And lastly, Carl J Lydick (RIP) and his **** for brains comments.

cjjeeper · Dec 12, 2020

Thank you all, as always for all the help....

yeah it was never going to work. I did try the webpage but no go there either...finally got hold of the service folks.

For future reference......Xylem Aquaforce e-MT must have at least rev 1.95 or higher software to utilize Modbus TCP/IP.

When installing the firmware/software upgrade....select Danforth Modbus TCP...

Modbus TCP/IP

cjjeeper

Member

id10t_error

Lifetime Supporting Member

widelto

Member

Ken Roach

Lifetime Supporting Member + Moderator

id10t_error

Lifetime Supporting Member

widelto

Member

cjjeeper

Member

drbitboy

Lifetime Supporting Member

cjjeeper

Member

Toine

Member

Ken Moore

Lifetime Supporting Member

BachPhi

Member

cjjeeper

Member

Similar Topics