Opto22 PAC Control REST API
Browse all Opto22 APIsOfficial vendor OpenAPI document · agent-readyIOTDevice Managementbasic55 EndpointsREST
For Agents
Read and write SNAP-PAC controller strategy variables and analog or digital I/O points over HTTPS using an API key in HTTP Basic Auth.
Use for: Read all int32 variables in the SNAP-PAC strategy, Get the engineering units of an analog input by name, Write a new value to a float variable on a SNAP-PAC, Set the state of a digital output on the controller
Not supported: Does not handle PAC strategy compilation, firmware updates, or groov-family controllers - use for SNAP-PAC named variable and I/O access only.
The PAC Control REST API provides HTTPS access to variables and I/O tags running inside an Opto 22 SNAP-PAC-R or SNAP-PAC-S series industrial controller. It exposes the controller's strategy, letting external systems read and write integer, float, string, and table variables, plus analog and digital I/O points by name. Authentication is HTTP Basic Auth carrying an API key id and value, and JSON payloads are capped at 3KB to match the controller's onboard buffer.
Install Jentic One Beta
Connect the PAC Control REST API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the PAC Control REST API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
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Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fopto22.com%2Fopto22-pac" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fopto22.com%2Fopto22-pac" | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with PAC Control REST API.
Read scalar strategy variables by name from a SNAP-PAC controller
Write values to integer, float, and string variables on the controller
Read analog input engineering units for a named I/O point
Set analog output values and digital output states
Read and write table variables across int32, float, and string types
Query controller and strategy metadata for routing and validation
Use Cases
Patterns agents use PAC Control REST API for, with concrete tasks.
★ Plant Variable Bridge to Higher-Level Systems
Expose SNAP-PAC strategy variables to an MES, SCADA, or analytics system without writing custom controller code. The REST API returns named int32, float, and string variables as JSON, so an integration can map them directly to records in the upstream system.
GET /device/strategy/vars/int32s to read all integer variables and post them to a time-series database every 60 seconds
Recipe and Setpoint Push from ERP
Allow an ERP or scheduling system to push job recipes into a SNAP-PAC by writing named variables on the controller. The named-variable model means the integration code does not need to track register addresses - it writes by symbol.
POST a JSON value to the named float variable for the recipe target temperature when an ERP job is released
Engineering Units for HMI Tiles
Drive HMI tiles or operator dashboards directly from analog inputs on a SNAP-PAC by requesting the engineering-unit value of each named I/O point. The dedicated /eu endpoint returns the scaled value the controller already computed, so the dashboard does not need to repeat scaling logic.
GET /device/strategy/ios/analogInputs/{ioName}/eu for each gauge tile every 2 seconds
Table Variable Inspection for Diagnostics
Read large table variables - int32, float, or string - from a SNAP-PAC strategy to inspect history buffers, alarm queues, or batch logs that the controller maintains in memory. The REST API exposes both whole tables and single indexed elements.
GET the named float table variable to download the last 100 batch results into a diagnostics report
Agent-Driven SNAP-PAC Operations via Jentic
An AI assistant for controls engineers can read and write SNAP-PAC variables and I/O points through Jentic without exposing the API key id and value to the model. The agent searches by intent and Jentic returns the matching named-variable read or write operation.
Search Jentic for 'write a value to a SNAP-PAC float variable', load the operation schema, and execute against the engineer's controller
Key Endpoints
55 endpoints — the pac control rest api provides https access to variables and i/o tags running inside an opto 22 snap-pac-r or snap-pac-s series industrial controller.
METHOD
PATH
DESCRIPTION
GET
/device
Get device info
GET
/device/strategy
Get running strategy info
GET
/device/strategy/ios/analogInputs/{ioName}/eu
Read analog input engineering units
GET
/device/strategy/ios/digitalInputs/{ioName}/state
Read digital input state
GET
/device/strategy/ios/analogOutputs
List analog outputs
GET
/device
Get device info
GET
/device/strategy
Get running strategy info
GET
/device/strategy/ios/analogInputs/{ioName}/eu
Read analog input engineering units
GET
/device/strategy/ios/digitalInputs/{ioName}/state
Read digital input state
GET
/device/strategy/ios/analogOutputs
List analog outputs
Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the PAC Control REST API by hand means building the Basic Auth header from the API key id and value and navigating its named-variable and I/O route tree on the SNAP-PAC controller yourself. Through Jentic you install once, import the PAC Control REST API from the API Directory, store the credential once, and your agent calls it.
Permission scoping
PAC Control puts the I/O point name in the URL path (/device/strategy/ios/analogInputs/{ioName}/eu), so a rule can pin your agent to reading one input. You choose the operations it may call, so output writes are not included unless you add them.
Credential isolation
Your PAC Control key id and value are stored once, encrypted, by your own Jentic One instance as a single Basic Auth credential and injected at execution time. They never enter the agent's prompt, logs, or context.
Intent-based discovery
Agents search Jentic by intent such as 'write a value to a SNAP-PAC float variable' or 'read an analog input', and Jentic returns the matching named-variable operation with its parameter schema so the agent calls the right endpoint without browsing the reference docs.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using PAC Control REST API through Jentic.
What authentication does the PAC Control REST API use?
HTTP Basic Auth with an API key. The API key id is sent as the username and the API key value as the password. Through Jentic, both halves are stored encrypted in the vault and the agent never sees the raw credential.
Can I write to strategy variables and I/O points with the PAC Control REST API?
Yes. The API exposes named writes for int32, float, and string variables and for analog and digital output points. Writes are constrained to a 3KB JSON body - fine for individual setpoints but not bulk table loads in a single call.
How many endpoints does the PAC Control REST API expose?
Fifty-five endpoints covering device info, the running strategy, scalar variables, table variables, and analog and digital I/O. The surface mirrors the named-variable model that PAC Control programs use, so endpoint paths follow the variable and I/O point names.
What is the maximum payload size for a PAC Control request?
The vendor docs cap JSON payloads at 3KB (3072 bytes) for both POSTs and GETs. Designs that need to read or write many table elements at once should chunk the calls below that limit.
How do I read an analog input through Jentic?
Install the SDK with pip install jentic, then search Jentic for 'read an analog input value from a SNAP-PAC'. Jentic returns the GET /device/strategy/ios/analogInputs/{ioName}/eu operation with its schema; load it, supply the I/O point name, and execute. Run it through Jentic One, the self-hosted execution layer.
Can I limit what my agent is allowed to do with the PAC Control REST API?
Yes. Jentic One is self-hosted, so your own rules decide which of the 55 operations and which Basic Auth credential the agent may use. Because PAC Control puts the I/O point name in the URL path, such as GET /device/strategy/ios/analogInputs/{ioName}/eu, you can pin the agent to reading a single analog input or a specific set of named variables. You pick the operations it can call, so analog and digital output writes are excluded unless you explicitly add them.
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