Overview

CommunicationJob is a built-in device communication scheduled task in UniCon. It retrieves registered driver instances via IDriverRegistry and executes periodic read or periodic write operations on target physical device addresses when triggered by a specified Cron expression.

The read/write results are recorded in the logging system. The task utilizes context.CancellationToken provided by Quartz to handle task cancellation and employs reflection to support read/write calls for arbitrary generic data types.

Prerequisite: The target driver must already be registered via IDriverRegistry.Register() and its connection state must be online (IsConnected == true); otherwise, the task will skip execution.

Usage

Register the task through JobScheduler.ScheduleJobAsync<CommunicationJob>() and pass parameters using the JobDataMap:

await jobScheduler.ScheduleJobAsync<CommunicationJob>(
    jobId: "ReadTemperature",
    cronExpression: "0/10 * * * * ?",  // Every 10 seconds
    data: new JobDataMap
    {
        [JobDataKeys.CommDriverId]  = "PLC_Line1",
        [JobDataKeys.CommAddress]   = "DB1.DBD0",
        [JobDataKeys.CommOperation] = "Read",
        [JobDataKeys.CommDataType]  = "System.Single"  // float
    }
);

Parameters

Pass the following key-value pairs through JobDataMap (accessed via the JobDataKeys constant class):

JobDataKeys Constant	Actual Key Name	Type	Description	Required	Default Value
JobDataKeys.CommDriverId	Job_Comm_DriverId	string	The registered driver's unique ID (must be registered and online)	Yes	—
JobDataKeys.CommAddress	Job_Comm_Address	string	Target communication address (format is protocol-dependent, e.g., DB1.DBD0, holding:1)	Yes	—
JobDataKeys.CommOperation	Job_Comm_Operation	string	Operation type: "Read" or "Write" (case-insensitive)	No	"Read"
JobDataKeys.CommValue	Job_Comm_Value	object	Target value to write (Required for Write operations)	No	null
JobDataKeys.CommDataType	Job_Comm_DataType	string	Full name of the data type (e.g., "System.Single", "System.Boolean", "System.Int16")	No	"System.Object"

Returns

CommunicationJob executes asynchronously, and results are recorded in the logging system:

Condition	Log Level	Content
Read Completed	Information	Read Response: {UniconResponse}
Write Completed	Information	Write Response: {UniconResponse}
Driver Missing/Disconnected	—	Task silently skipped (no log)
Execution Exception	Error	CommunicationJob failed for {driverId}

Examples

Example 1: Periodic S7 temperature reading (float) every 10 seconds

await jobScheduler.ScheduleJobAsync<CommunicationJob>(
    jobId: "ReadTemperature",
    cronExpression: "0/10 * * * * ?",
    data: new JobDataMap
    {
        [JobDataKeys.CommDriverId]  = "PLC_Line1",
        [JobDataKeys.CommAddress]   = "DB1.DBD0",
        [JobDataKeys.CommOperation] = "Read",
        [JobDataKeys.CommDataType]  = "System.Single"
    }
);

Example 2: Automatic PLC counter reset (writing 0) at midnight daily

await jobScheduler.ScheduleJobAsync<CommunicationJob>(
    jobId: "ResetDailyCounter",
    cronExpression: "0 0 0 * * ?",  // Daily at 00:00:00
    data: new JobDataMap
    {
        [JobDataKeys.CommDriverId]  = "PLC_Line1",
        [JobDataKeys.CommAddress]   = "DB1.DBW10",
        [JobDataKeys.CommOperation] = "Write",
        [JobDataKeys.CommValue]     = 0,
        [JobDataKeys.CommDataType]  = "System.Int16"
    }
);

Example 3: Modbus meter current reading (int) every minute

await jobScheduler.ScheduleJobAsync<CommunicationJob>(
    jobId: "ReadMeterCurrent",
    cronExpression: "0 * * * * ?",  // Every minute
    data: new JobDataMap
    {
        [JobDataKeys.CommDriverId]  = "Meter_01",
        [JobDataKeys.CommAddress]   = "holding:30001",
        [JobDataKeys.CommOperation] = "Read",
        [JobDataKeys.CommDataType]  = "System.Int32"
    }
);

Example 4: Publish gateway heartbeat to MQTT every 30 seconds

await jobScheduler.ScheduleJobAsync<CommunicationJob>(
    jobId: "MqttHeartbeat",
    cronExpression: "0/30 * * * * ?",  // Every 30 seconds
    data: new JobDataMap
    {
        [JobDataKeys.CommDriverId]  = "Cloud_Broker",
        [JobDataKeys.CommAddress]   = "gateway/heartbeat",
        [JobDataKeys.CommOperation] = "Write",
        [JobDataKeys.CommValue]     = "{\"status\": \"alive\"}",
        [JobDataKeys.CommDataType]  = "System.String"
    }
);

Contributors: Entity-now