Siemens SIWAREX weighing technology: software, connection and integration

What we do for Siwarex users

• Read weighing values out of the S7 PLC and post them to ERP systems
• Historise weighings and batch data in databases
• Create analyses and reports on throughputs, consumption and recipes
• Link weighing processes in the plant to orders and article master data
• Connect existing Siwarex installations without changing the control logic

Supported devices and series

SIWAREX components we regularly work with:

• SIWAREX WP231 / WP241 / WP251 for S7-1200: platform and hopper scales, belt scales, filling and dosing
• SIWAREX WP321 / WP351 for ET 200SP and WP521 / WP522 ST for S7-1500: single- and dual-channel weighing modules in modern plants
• SIWAREX FTA / FTC / U / CS: legal-for-trade and classic modules in existing S7-300/400 installations
• SIWAREX load cells WL200, WL230, WL260, WL270 and WL280 as well as weighing modules on hoppers and silos

Weighing technology in the PLC world

Unlike a bench scale with a display, a Siwarex module sits directly inside the automation system: the load cells are wired to the module, the weight values are available in the PLC and are used there for dosing, filling or fill-level monitoring. For the IT side this means: the data exists, but it is „locked up“ in the PLC. This is exactly where we come in – with clean, read-only access to defined data points that become reliable business data. What such a coupling between scale, PLC and IT typically looks like is described on our page Connecting a scale to a PLC via OPC UA.

Interfaces, connection and integration

SIWAREX modules sit on the PLC's backplane bus; externally, the weight values are available via Profinet, Profibus, Modbus RTU/TCP (WP231, WP321) or – on the S7-1500 – OPC UA. We read out weight, status and, on FTA modules, the alibi memory, transfer values into a database, MES or ERP, generate batch and consumption records and provide dashboards on fill levels and throughputs. Parameterisation of the modules (SIWATOOL) remains with the automation engineer; we work on the released data blocks and communication paths.

Frequently asked questions

How do the weighing values get from the S7 PLC into our ERP?

The Siwarex modules deliver the weight values to the PLC – from there we fetch them via OPC UA or other suitable communication routes and hand them over to ERP, a database or reporting. The control logic remains unchanged; our software reads along without interfering with the process.

Do we have to have the PLC program changed for this?

In many cases, no. If the relevant values are already present in the PLC, read-only access is enough. If adjustments are needed, we coordinate with your PLC programmer or plant builder and define the data points together.

Does this also work with an S7-1200 and WP231?

Yes. More compact configurations – such as Siwarex WP231, WP241 or WP251 on an S7-1200 – can be connected too. What matters is which communication routes your specific plant offers; we clarify that in a short survey.

Can you transfer SIWAREX weight values from the S7 into our MES or ERP?

Yes. Via OPC UA, Profinet or Modbus we read the weight values and status from the PLC, assign them to the order, batch or material and post them to the MES or ERP – cyclically, event-driven or as a batch total.

We have legal-for-trade SIWAREX FTA modules – can the alibi memory be used on the software side?

Yes. The FTA modules store legal-for-trade weighings with a number in the alibi memory. We take this number into the weighing ticket and data record so that every posting can be traced back to the value secured under legal metrology.