# Ignition

Ignition tags and history right in the chat

Теги и история Ignition через модуль WebDev и шлюз, только чтение

## How the agent works with Ignition

The gateway runs as a service on a computer on the site network and reaches the Ignition gateway over HTTP. Values and history are read through four WebDev resources imported into one project: about, tags, values and history. The connection takes the address of their folder, the account login and password, the tag provider and, if you like, the folder to start from.

The Ignition 8.3 Gateway REST API configures the gateway but returns neither tag values nor history, and the Ignition OPC UA server does not support HistoryRead. So the resources call system.tag.readBlocking and system.historian.queryRawPoints on 8.3, or system.tag.queryTagHistory on 8.1. History is read in 15 minute windows, so a SQL Historian does not reread the whole period on every page.

Every resource answers GET only and none writes a tag, and the connection account gets no write rights. The gateway uses no proxy and follows no redirects, so the account is never carried to another host. Arrays, DataSet and Document tags are not declared: they hold no value the gateway carries.

The gateway reads each tag's archive forward from where it stopped, with a one minute overlap, so an event Ignition store-and-forward wrote late still arrives. After downtime the gateway reads what it missed, but no further back than a week. Tags without history are read by their current value at the poll interval, 10 seconds by default.

## Integration scenarios

### What is on the line now
The agent finds the provider's tags by name or description and shows current values with units, time and quality.

### A shift trend
The agent reads a tag's history from the Ignition historian for a shift or a week and names the minimum, maximum, average and range breaches.

### Tags with bad quality
The agent finds tags with bad or uncertain quality and shows the Ignition quality code and the time it has stood since.

### Comparing lines
The agent compares the same tags of different folders or lines over a period and shows where the values part.

### A threshold message
In an event task the agent tells you when a tag's value crosses a threshold and holds for the set time, and when it is back to normal.

### Link to the site
The agent tells you when the gateway went offline and came back. The gateway reads the history of the break from the Ignition archive.

## How to connect

**Before you connect**

- Ignition 8.1 or 8.3 with the WebDev module
- The gateway resources imported into one Ignition project
- A user source account with no right to write tags
- Access from the gateway computer to the gateway web port (8088 by default)

### Check the WebDev module
The gateway reads Ignition through WebDev module resources. Make sure the module is installed on the Ignition 8.1 or 8.3 gateway.

### Import the resources into a project
In Designer add the project library equipment_gateway and, in WebDev, a folder equipment-gateway with resources about, tags, values, history, each with doGet only.

### Add an account without write rights
Require authentication with a user source for the resources and add an account with no right to write tags. Enter its login and password in the connection.

### Enable history on the tags you need
History is read for tags with History Enabled. The gateway reads other tags by their current value.

### Open the gateway web port
The gateway computer needs access to the Ignition web port, 8088 by default. The folder address is http://host:8088/system/webdev/Project/equipment-gateway.

## FAQ

### How do I connect Ignition?
Import the equipment_gateway library and the WebDev folder equipment-gateway with resources about, tags, values and history into a project and require authentication for it. Install the gateway on the site network, add it on the Gateways tab and enter the folder address such as http://10.0.12.5:8088/system/webdev/Project/equipment-gateway, a login and password.

### What does the agent see in Ignition?
Atomic tags of the chosen provider and folder with type, units, range and description, their current values with quality, and the history of tags that have it enabled. The gateway reads the Ignition version from the about resource.

### Does the agent change tag values?
No. The resources answer GET only and call only tag and history read functions, and the gateway cannot send any other request. The connection account gets no right to write tags.

### Why do some tags have no history?
The gateway reads the archive only for tags with History Enabled. Others it reads by current value, and their history builds up from those polls. If the historian refuses a tag's history request, that tag also switches to current value reads.