A PLC automation quotation is only comparable when the process, equipment, I/O, interfaces and testing responsibilities are defined. A brand name or a list of components is not enough to establish what the control system must do on site.
This guide is for engineers, EPC teams, project managers and industrial buyers preparing a control-system RFQ. It focuses on practical information to send for clarification, the questions to keep open and the evidence to request before the scope becomes contractual.
1. Define the process and control scope
Begin with a plain-language description of the equipment or process and the result the control system must achieve. Include the operating modes, manual and automatic controls, alarms, trips, interlocks, sequences, outputs and the conditions that require buyer or operator intervention.
| Input | What the buyer should provide | Why it matters |
|---|---|---|
| Process description | Equipment, sequence, operating modes, process constraints and controlled variables. | Defines the functional scope before component selection. |
| Equipment list | Motors, pumps, valves, heaters, instruments, sensors, actuators and remote equipment. | Links control channels to the physical plant. |
| Safety and protection boundary | Project safety requirements, protection devices, emergency stops and responsibility for each function. | Prevents design assumptions across mechanical, electrical and control disciplines. |
| Operating environment | Indoor or outdoor, temperature, humidity, dust, wash-down, altitude and access conditions. | Drives cabinet, component and thermal requirements. |
| Project interfaces | SCADA, BMS, electrical switchgear, cable routes, field instruments and other panels. | Identifies signals, protocols, power and documentation boundaries. |
2. PLC, I/O and HMI requirements
For the PLC and operator interface, state the information that affects the architecture and quotation:
- PLC platform: preferred manufacturer, family, series, controller quantity and any required part numbers.
- I/O schedule: digital and analogue inputs and outputs, signal types, voltage or current, channel counts and spare capacity.
- Power supply: control voltage, redundancy expectation, protection, isolation and power-loss or restart behaviour.
- HMI: screen count, display size, operator functions, alarms, recipes, trends, language, access levels and remote requirements.
- Expansion: future I/O, additional panels, network devices, software options and reserve capacity.
Where the design is incomplete, a marked-up I/O list or functional description can start the clarification round. The buyer should identify which values are fixed by the project and which can be proposed by the selected manufacturing partner.
3. VFDs, motor control and power interfaces
For motor-control projects, provide the motor list and define the relationship between the drive, protection, contactor, starter, feedback device and control signals. Include motor ratings, starting method, speed or torque requirements, braking or regeneration needs, cable lengths and the applicable protection arrangement.
- State whether VFDs are buyer-specified, partner-proposed or open for an equivalent proposal.
- Identify the required input and output filtering, harmonic, line and load-side requirements where relevant.
- State the required local controls, emergency stop, isolation, overload protection and status feedback.
- Coordinate the control panel with the power distribution, busbar, cable tray and field-cable design.
- Mark any requirements that need engineering review, such as functional safety, network segmentation or remote access.
Keep capability boundaries explicit. AMG can coordinate the inquiry and clarify the requested scope with selected manufacturing partners. The existence, brand and technical fit of a platform, software package, programming service or commissioning resource must be confirmed for the specific project.
4. Communications, SCADA and network questions
For any SCADA, BMS or plant-network interface, state the protocols, device list, data points, network topology, interface responsibility and any required security or access-control requirements. Avoid assuming that a standard protocol list is sufficient; confirm the actual version, operating role and information flow.
| Interface | Buyer information | Clarification item |
|---|---|---|
| Field devices | Device type, signal, power, address, protocol and location. | Who supplies, terminates, tests and documents the device? |
| SCADA or BMS | Platform, protocol, data points, alarms, trends, users and network boundary. | What is the handover and configuration responsibility? |
| Drive and switchgear | Control signals, status, trips, meters and protection interfaces. | Which signals are hardwired, communicated or exposed for integration? |
| Remote or service access | Required access, security policy, account process and site connectivity. | Which requirements are project-specific and who approves them? |
Network segmentation, cybersecurity and functional-safety requirements should be stated as project requirements and reviewed by the responsible engineer. They should not be presented as a default capability unless the selected partner confirms them for the inquiry.
5. FAT, SAT and commissioning responsibilities
Testing is part of the procurement scope. Define where each activity happens and what evidence closes it.
| Stage | Typical questions for the buyer to define |
|---|---|
| Factory testing | What is tested before shipment: I/O simulation, power checks, wiring, logic, HMI, alarms, communications and documentation? |
| Site acceptance | Which field signals, loops, interlocks, drives, instruments and network interfaces are tested on site? |
| Commissioning | Who performs programming, configuration, loop checks, functional tests, data loading and defect correction? |
| Witnessing | Who attends, when is the procedure issued, how are deviations recorded and what is the acceptance authority? |
| Handover | Which drawings, programs, configurations, passwords, manuals, backups, training records and as-built documents are required? |
State whether a FAT or SAT is being requested as a project requirement, what the test script must cover and how the selected manufacturing partner should report results. A generic promise that testing is included is not enough for a comparable quotation.
6. Documents, software and handover
Ask the supplier to identify the document and configuration package before the order is placed. Depending on the project, this may include:
- GA drawings, internal layouts, wiring diagrams, terminal schedules and component lists.
- I/O lists, HMI screen lists, alarm lists, control narratives and approved test procedures.
- PLC, HMI, VFD and network configuration files, backups or project copies, subject to the buyer's security and confidentiality requirements.
- Programming and commissioning records, FAT/SAT records, punch-list closure and training or handover records.
- Applicable standards, conformity evidence, manuals, spare-parts information and maintenance requirements.
Confirm the language, file format, delivery method, revision control and ownership or access arrangements for project files. Do not assume that software, licences, source files or remote support are included unless they are expressly stated in the quotation.
7. Practical PLC and automation RFQ checklist
- Project description, process overview and controlled equipment list.
- Functional description, operating modes, alarms, trips and interlocks.
- I/O list, signal types, channel quantities and spare capacity.
- PLC, HMI, VFD and other platform or brand preferences.
- HMI screens, operator roles, language and data requirements.
- Communication protocols, network topology, SCADA/BMS and field-device interfaces.
- Power supply, control voltage, protection, isolation and restart requirements.
- Cabinet dimensions, mounting, environment, IP and thermal requirements.
- FAT, SAT, commissioning, witness, training and handover responsibilities.
- Documentation, software/configuration, spare parts, destination, delivery and inspection requirements.
If the I/O list or control narrative is not ready, send the information currently available and mark the open items. The first clarification round can identify the minimum data needed for a budgetary quotation without guessing the final design.
8. How AMG coordinates automation sourcing
AMG is an international industrial sourcing and supplier-coordination company working with selected Chinese manufacturing partners. AMG is not the manufacturer. For a PLC or automation inquiry, AMG can organize the process description, I/O information, platform preferences, control cabinet requirements, network interfaces, testing scope and delivery questions before coordinating clarification with suitable selected partners.
Where appropriate, AMG can coordinate automation alongside control cabinets, custom enclosures, low voltage switchgear, distribution systems, busbars and cable management. Final platform availability, software scope, programming, commissioning, documentation and commercial terms are confirmed per project.
9. Frequently asked questions
What should a buyer provide for a PLC automation RFQ?
Provide the process description, equipment list, I/O list, PLC platform preference, HMI requirements, communication protocols, motor and VFD information, control logic, drawings, cabinet dimensions, power requirements, testing and commissioning expectations, destination and applicable project standards.
How should FAT, SAT and commissioning responsibilities be defined?
State which party performs factory testing, site acceptance testing, programming, functional testing, loop checks, network integration and commissioning. Define the approved test procedures, witnesses, records, punch-list process, software or configuration handover and responsibility for unresolved items.
Can buyers specify PLC, HMI and VFD brands?
Yes, where the project requires them. State the required brands, exact series or part numbers, approved alternatives and the approval process for substitutions. Availability, technical fit and commercial impact are confirmed with the selected manufacturing partner during clarification.
Can AMG coordinate automation controls with electrical equipment?
Yes. AMG coordinates project requirements with selected Chinese manufacturing partners and can organize PLC, HMI, VFD, control cabinet, power distribution, busbar and cable management scope where appropriate. AMG is not the manufacturer and final capability, software, commissioning scope and commercial terms are confirmed per inquiry.
Prepare a PLC and automation RFQ
Send the process description, I/O list, control narrative, drawings and project environment. AMG can organize the first clarification round with a suitable selected manufacturing partner.