Connecting Existing PLCs and Equipment to SCADA
Many plants have PLCs, compressors, HVAC units and older controllers whose data is only shown locally or travels on an older network. TDL connects them to a new or existing SCADA over Modbus, BACnet, DH+ or EtherNet/IP, usually keeping the existing controller and its logic in place.
What TDL does
Serial Modbus devices
Modbus RTU ports of PLCs and packaged equipment connected through Modbus RTU to Modbus TCP gateways.
BACnet equipment
BACnet/IP HVAC equipment brought into the SCADA through gateways and KEPServerEX.
Project references
DH+ and older networks
Existing PLC-5 controllers connected to a new HMI through DH+ to EtherNet/IP converters.
Links to the plant ICSS or DCS
Modbus TCP links between package controllers and the platform ICSS or DCS added or kept during upgrades.
PLCs of other makes
Existing PLCs of other makes, such as Mitsubishi, stay in control while their data is shown on the new SCADA.
Project references
SCADA, alarms and history
New tags, graphics, alarms and historian entries for the connected equipment, with web access from browsers where needed.
Related services
SCADA & Plant Data Integration
SCADA and HMI on FactoryTalk View SE/ME, FactoryTalk Optix, AVEVA System Platform, AVEVA InTouch HMI (formerly Wonderware InTouch), AVEVA Edge (formerly InduSoft Web Studio), Ignition and N3uron. Thin clients with ThinManager. Historians (FactoryTalk Historian, AVEVA Historian, AVEVA PI System), FactoryTalk Batch, OPC UA, Kepware and MES integration.
Industrial Networks & OT Security
EtherNet/IP networks on Stratix managed switches, with redundancy by DLR rings, PRP and HSR. VLAN segmentation, firewalls and secure remote access following IEC 62443 zone and conduit principles. Interfaces to third-party systems over Modbus and OPC UA.
Project references
- 2026 – Yakult Vietnam – Ice Bank Monitoring SCADA on FactoryTalk OptixFactoryTalk Optix SCADA · Mitsubishi PLC over Modbus · web access · ice bank utility
- 2025–2026 – SEHC – New Air Compressor Integrated into FMCS SCADAAir compressor into FMCS · Modbus · AVEVA System Platform · central control room
- 2025–2026 – SEHC Admin Building – AHU and OAC Monitoring SystemAVEVA System Platform · BACnet/IP to Modbus TCP · historian and reporting
- 2023 – PV GAS Vung Tau Terminal (Thi Vai) – Loading Arm System HMI ReplacementRSView32 → FactoryTalk View SE · DH+ to EtherNet/IP · existing PLC-5 kept
- 2020 – Vietsovpetro Central Compressor Platform – EDG and Switchgear Control System UpgradeSLC 500 → CompactLogix · FactoryTalk View SE · Modbus TCP to ICSS · 8-day shutdown
Frequently Asked Questions
Does the existing PLC program have to change?
Usually not. At Yakult Vietnam the existing Mitsubishi PLC stays in control and its data is read over Modbus; at Thi Vai the PLC-5 controllers were kept and connected through DH+ to EtherNet/IP converters.
Which SCADA platforms are used?
FactoryTalk View SE, FactoryTalk Optix and AVEVA System Platform in the projects on this page; Ignition and N3uron are also options.
Can the new data go to a historian?
Yes. At SEHC the air compressor and AHU data were added to the historian and the automated reports.
Want data from existing PLCs and equipment in your SCADA?
Speak directly with our engineers. Your RFQ, scope of work or drawings are answered by the engineers who program and commission the systems, from the first review of the existing system to the proposed solution.
Email sales@tdl-ia.com.vn Request a site survey Hotline · Urgent breakdown support