Scale Integration Overview

Tempo leverages the No-Code OPC UA Integration to integrate with scales. There are a few technical requirements to enable the scale integration to function, which will be detailed below:

Mandatory Requirements

• The scales must be networked and communicating with an OPC UA server to which Tempo can communicate. For information about establishing private connectivity please see Establishing Private Connectivity with Apprentice.

Specific Function Support and Technical Constraints

• Tare and Zero commands are embedded and performed in material process actions (Dispense, Consume, and Output).

• Tare and Zero can be performed outside of the material process actions but may require separate configuration depending on your integration set up.

Scale Integration Architecture

The following diagram shows a high level architecture example of integrating scales with Tempo utilizing OPC UA middleware.

The following diagram shows a the technical data flow and components that allow Tempo and Scales to exchange data.

flowchart BT
  subgraph delivery["Real-time delivery"]
    direction LR
    pubnub["Managed pub/sub (PubNub)<br/>Per-session weight channel"] -- "Live weight" --> apps["Tempo apps<br/>iOS and Web subscribe"]
  end

  subgraph cloud["Apprentice cloud"]
    direction LR
    api["Platform API<br/>Tare and Zero commands"] --> intsvc["Integration service<br/>OPC UA client, polls weight"]
  end

  subgraph conn["Private connectivity (choose one)"]
    direction LR
    vpn["Site-to-site VPN<br/>IPsec tunnel"] ~~~ pl["AWS PrivateLink<br/>Requires customer AWS"] ~~~ edgedev["Edge device<br/>Outbound TCP 443 only<br/>Would host the OPC UA server"]
  end

  subgraph plant["Customer plant network (on-prem)"]
    direction LR
    scale["Weighing scale<br/>Mettler Toledo, Sartorius"] --> opcua["OPC UA server<br/>e.g. Mettler Toledo, Kepware KEPServerEX,<br/>OPC Router, Matrikon<br/>(may run on the edge device)"]
  end

  plant <-- "Weight readings up,<br/>Tare / Zero writes down" --> conn
  conn <-- "OPC UA secure channel (X.509, TLS)<br/>cloud-initiated, carries reads and writes" --> cloud
  cloud -. "Publishes readings" .-> delivery
  delivery -- "Tare / Zero" --> cloud

  classDef plantNode fill:#E1F5EE,stroke:#0F6E56,color:#085041
  classDef connNode fill:#F1EFE8,stroke:#888780,color:#2C2C2A
  classDef cloudNode fill:#EEEDFE,stroke:#534AB7,color:#3C3489
  classDef deliveryNode fill:#FAECE7,stroke:#993C1D,color:#712B13
  class scale,opcua plantNode
  class vpn,pl,edgedev connNode
  class api,intsvc cloudNode
  class pubnub,apps deliveryNode

  style plant fill:transparent,stroke:#B4B2A9,stroke-dasharray:5 5
  style conn fill:transparent,stroke:#B4B2A9,stroke-dasharray:5 5
  style cloud fill:transparent,stroke:#B4B2A9,stroke-dasharray:5 5
  style delivery fill:transparent,stroke:#B4B2A9,stroke-dasharray:5 5

How the Integration Communicates

• Tempo applications never connect directly to a scale — there are no scale drivers or device connections on operator tablets or workstations. All device communication is handled by Apprentice's cloud integration service, which connects to your OPC UA server as an OPC UA client.

• Weight readings flow from the scale to your OPC UA server, are polled by the integration service, and are streamed live to the operator's app on a per-session channel for the duration of the weighing operation.

• Tare and Zero commands flow in the opposite direction over the same connection — from the app through the Apprentice cloud to your OPC UA server as a method call or tag write.

• The OPC UA session is initiated by the Apprentice cloud and secured with X.509 certificates over an encrypted channel, with configurable OPC UA Security Policy and Message Security Mode. Unknown server certificates are rejected, and integration credentials are stored encrypted.

Private Connectivity Options

The connection between the Apprentice cloud and your plant network is established over one of three private pathways — traffic never traverses the public internet. For full details please see Establishing Private Connectivity with Apprentice.

• Site-to-Site VPN: a dedicated IPsec tunnel into your data center or facility. Ideal for organizations with existing VPN infrastructure.

• AWS PrivateLink: cloud-native connectivity to an endpoint service in your own AWS account. This option applies only if your target systems run in your own AWS environment.

• Edge Device: a gateway appliance deployed in your network that initiates an outbound connection on TCP 443 only — no inbound firewall ports are required. The edge device can also host the OPC UA server itself.

Below is a list of common OPC UA middleware vendors in the industry that can facilitate connectivity between scales and Tempo:

• Kepware KEPServer

• OPC Router

• Ignition SCADA

• Matrikon

• Mettler Toledo ACI400 Edge Device

• Cogent Datahub

• Integration Objects

• Top Server and Omniserver

Hosting OPC UA Middleware on the Apprentice Edge Device

When the Edge Device connectivity option is used, the OPC UA middleware can run on the edge device itself. The edge device also runs the Apprentice Edge middleware, which provides data flows with connectivity for serial (RS-232/485) devices, Modbus TCP, PLCs, MQTT, REST APIs, and SQL databases.

Setting up Equipment Class/Subclass and Instance for Scale Integration

The following steps will guide you on configuring a Tempo Equipment Instance with Scale Integration.

Using Scales with Material Actions during Execution

Tempo material process actions (Dispense, Consume, and Output) are designed to be flexible in how the weighing data is captured. The following table illustrates which options are available in the respective material action.

Manual: The operator manually enters the scale weight value as it appears on the scale or associated HMI. When completing, operator signature and reason is required.

Scale Weighing: The operator scans a Tempo scale equipment instance that has been integrated. If configured on the material action, the operator will be instructed to zero and/or tare the scale, which can be done through the app if supported by the integration configuration. During the weighing operation, the weight value is read directly from the integrated scale every 0.5 seconds until the operator completes the material operation. No signature or reason is required when completing.

Bulk: The operator scans a Tempo material sublot barcode which automatically pulls in the total quantity of that sublot. No signature or reason is required when completing.