Supply of PLC sets and network switches for Tower Lamp work on the packing line of an FMCG food factory in Thailand

How the brief came about

An FMCG food factory in Thailand needed 25 identical sets of control and network equipment for its packing line. The project name states that they were for Tower Lamp signal light work, while the purchase order describes them as hardware for syncing barcode scanner data on the packing line into the CIM system.

CIM (Computer Integrated Manufacturing) is a system that brings a factory's production data together in one place. The documents for this work do not state at which point on the line each set is installed.

Requirements and constraints

The main requirements of this work came from the purchase order, which already specified the models and quantities of equipment for every set.

• The purchase order specified the same models for every set: a Siemens LOGO! PLC, a 5-port Gigabit network switch, and LAN cables and connectors.
• A single purchase order covered all 25 sets.
• The items in the quotation and purchase order for these sets are all equipment.

Why every set uses the same equipment models

Every set uses the same equipment models because the purchase order specified the same models for every set. We sourced and delivered all 25 sets to match those models.

For factories in general, using the same equipment model at every point helps with spare parts, because a failed set can be replaced with the same model of equipment using the same configuration.

What each delivered equipment set contains

Each equipment set has a PLC, a network switch, and LAN cables and connectors. We delivered 25 sets in total. The details are as follows.

In 2023 we also delivered 32-inch displays with stands and Raspberry Pi kits (small single-board computers), 2 sets of each, with the Raspberry Pi configured for use with the displays. This work was under a separate purchase order. The documents do not state that the displays show data from the PLC sets above.

The batched delivery process

We delivered the first batch of 10 sets in July 2023 and the second batch of 15 sets in August 2023 under a single purchase order. The sequence of work was as follows.

1. 1

   Issue the quotation

   Propose the equipment models and quantities per set as the factory required, 25 sets in total.

2. 2

   Receive the purchase order

   The factory issued a single purchase order covering all 25 sets.

3. 3

   Deliver the first batch

   Delivered 10 sets in July 2023 with delivery documents.

4. 4

   Deliver the second batch

   Delivered a further 15 sets in August 2023, completing the purchase order.

Results confirmed from the delivery documents

The confirmed results of this work are delivery of all 25 sets under the purchase order; each of the 2 batches has delivery documents referring to the same purchase order, and the annual project summary for 2023 records the work as completed.

This case is an equipment supply job. We have no documents on performance in use after delivery, so we report only the delivery backed by documents.

What we learned

This work offers the following principles for supplying control and network equipment across multiple points.

• Specify the same equipment models for every set from the purchase order onwards. Identical sets can use the same PLC program and network configuration.
• Separate equipment items from service work clearly in the quotation. If you need programming or on-site installation, list it as a separate item, so that the buyer and seller share the same understanding of the scope of work.
• A single purchase order stating the models and quantities per set serves as the reference document for acceptance of every batch. When the documents for every batch refer to the same purchase order, checking the outstanding balance is straightforward.

How this approach can apply to your factory

If your factory needs to place signal lights or connect barcode scanners to a central data system at multiple points, you can define one standard equipment set and order the quantity you need under a single purchase order. What needs adjusting is the equipment model and scope of work, when your signal count or network differs from this case.

• Count the input and output signals each point needs, then compare them with the chosen PLC model.
• Check the factory's network layout and the permissions for connecting new devices to CIM or the central data system.
• State clearly whether you want supply only, or programming and installation as well.