The web server on an HMI panel has no alarms.jpg page and no alarm tag. Put an alarm object on a numbered screen and request that screen's image, such as http://192.168.2.1:80/3.jpg, or use Remote Access when someone must operate the panel from the browser.
The panel shows alarms on its own glass, and the web server can show them too, just not through a page of its own. There is no alarms.jpg and no alarm tag to read. The documented path is a numbered screen that carries an alarm object, requested as an image, or the Remote Access feature when someone must operate the panel from the browser. This page walks both: building the screen in the project, the exact URL form, the address to use from outside, and the checks that tell a wrong screen number from a panel-side alarm problem.
Is there an alarms.jpg page on the HMI web server?
No. The web server holds no alarm tag and no special page such as alarms.jpg. A URL of the documented form http://192.168.2.1:80/3.jpg always asks for a numbered screen, and the alarms appear only when that screen carries an alarm object.
The server does expose data values as tags, and reading PLC tag values from an HMI panel web server covers that half. Alarms have no equivalent address. Everything the browser shows must first exist as an object on a project screen, so the work happens in the programming software. The web server then serves that screen as a picture. Two documented paths cover every need: the numbered screen URL for reading, and Remote Access for operating.
What do you need before you start?
You need the panel's IP address, a browser on the same network, the programming software that builds the project, and the number of the screen that will carry the alarm history.
Open the panel's address in the browser first and confirm the start page appears. If it does not load, fix that before touching the project. Get the screen number from the project itself, because the number belongs to the screen. The order in which you created the alarms says nothing about it.
How do you put the alarm history on a screen?
Place an alarm object through the menu path Object > Alarm > Alarm History. Then choose between the Alarm History object and the Alarm Message object; the help file topics CM230 and CM044 document both.
- Open the project in the programming software.
- Go to Object > Alarm > Alarm History.
- Choose the object that fits the reader, using the table below.
- Place it on a screen of its own, or on a screen where operators already work.
- Save the project and download it to the panel through your site's normal change process.
- At the panel, open that screen and confirm the history shows locally.
| Object | What it places | Fit for a web page |
|---|---|---|
| Alarm History | A button that opens a pop-up alarm screen | For operators at the panel; a browser image cannot press the button |
| Alarm Message | The alarm screen itself, with no buttons | For reading from the browser; add key buttons only if someone must control it locally |
The documentation also describes an alarm list object that can display alarms as a full screen. It can also work as a banner at the bottom of a screen showing the active alarms, which suits a status screen with the history kept on its own numbered screen.
What URL shows the alarm screen in a browser?
Type the panel's IP address, a slash, the screen number and .jpg into the browser. The documented example is http://192.168.2.1:80/3.jpg, with 192.168.2.1 as the panel's address, 80 as the port and 3 as the screen.
Swap in your own panel address and your own screen number. The answer comes back as an image of that screen, which is the same reason an HMI web server sends a JPEG instead of tag text. The start page of the web server lists screens, each entry the same request by number. When the web page shows only 10 of your screens that listing has a known limit and fix.
When should you use Remote Access instead?
Use Remote Access when someone must acknowledge, clear or navigate alarms from the browser. The feature operates the panel as if that person stood in front of it, and the panel can hold up to 4 IP addresses, one of them for access from an external network.
From outside the plant network, use the address assigned to remote access. The feature is configured separately from the web server, so a start page that loads fine can still leave remote access missing from the web page. Check that configuration before assuming a network fault. Remote Access can also save a .jpg of a screen to disk for later review.
Keep one rule with both paths. A person who acknowledges an alarm from a browser is not at the machine, so leave reset and restart authority with someone who can see it.
What does a complete example look like?
A panel at 192.168.2.1 with the alarm history on screen 3 is read at http://192.168.2.1:80/3.jpg. A browser shown 12 ft away needs capitals of at least 0.4 in, or 0.6 in for fast reading.
Carry the numbers. The planning figure we apply to shop-floor screens is 30 ft of viewing distance per inch of letter height, so 12 ft ÷ 30 ft per inch = 0.4 in capitals. For fast reading use 20 ft per inch: 12 ft ÷ 20 ft per inch = 0.6 in. Line spacing at 1.7 times the capital height gives 1.7 × 0.6 in = 1.02 in per row. Set the alarm object's font so a timestamp row measures 0.6 in on the glass of the display that carries the browser. A 10 in tall block of that screen then fits 10 in ÷ 1.02 in per row = 9 rows of history.
That is the whole sizing check. The URL delivers the picture, and the font decides whether anyone can read it from where they stand.
How do you check it worked?
Open the URL and compare the picture with the panel beside it. Confirm three things: the browser shows the intended screen, that screen carries the alarm object, and the history matches what the panel itself displays.
Work the failures in order:
- The browser shows a different screen. The number in the URL is wrong. Read the screen's number in the project and retype the URL.
- The browser shows the right screen with no history. The object is missing from that screen; alarms configured elsewhere in the project stay off a screen that carries no alarm object.
- The panel itself shows no history either. Fix the local alarm configuration first. The web page mirrors the panel, and no URL adds history the panel does not display.
- The start page will not load, or loads and then stops answering. When the panel's web server stops responding while FTP still works, that is a server failure with its own fix, not a screen problem.
Recommendation: Put an Alarm Message object on its own numbered screen and read it through that screen's .jpg URL whenever the browser only has to show history. Move to Remote Access when operators must acknowledge or clear alarms from the browser, and confirm the panel's remote access address is reachable from their network before the first shift depends on it.
Questions
Can the alarm window be saved as an image for a report?
Yes. Remote Access can save a .jpg of a screen to disk over the network, and the documentation names alarm windows and trends among the items you can capture for later review. It is a capture at a moment you choose, so pair it with the numbered screen URL for the live view.
Which IP address do you use to reach the panel from another network?
Use the address assigned to remote access. A panel can hold up to 4 addresses: one per port, plus one for access from an external network. The panel's network setup displays all of them, so read the remote access address there and use it when the browser sits outside the plant network.
Will the alarm image update by itself in the browser?
The plain numbered URL returns the screen image taken at the moment of the request, so reload the page to request it again. A Remote Access session is the live, interactive path and is the one to use when the history has to move as alarms come and go.
Do key buttons have to be added to the Alarm Message object?
Only for operators standing at the panel. The Alarm Message object is the alarm screen with no buttons of its own, and you add key buttons when someone must control it locally. The browser image never uses those buttons, so leave them off a screen built only for the web page.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.