Frequently Asked Questions (FAQ)

Find quick answers about PLC controllers, expansion modules, DBUS/remote I/O, PLINK headers, software, wiring, compatibility, and ordering. If you don’t see your question here, contact us and we’ll help you select the right solution.

General

1) What product categories do you offer?

We provide PLC controllers (Smart 200 Standard/Economical, S7-200 series compatible), expansion modules (digital/analog/temperature), DBUS distributed remote I/O, and PLINK head + module systems for Ethernet/RS485 expansion.

2) Are your PLCs compatible with Siemens programming habits?

The product positioning is “compatible with S7-200 / S7-200 SMART ecosystems” for typical application scenarios, including I/O structure and common industrial use. For exact project migration scope, share your CPU model, program features, and required communications.

3) Can I get a recommended model list (BOM) for my machine?

Yes. Send your required DI/DO/AI/AO/temperature channels, communication needs (Ethernet/RS485), sensor type (PT100/NTC/Type K), and cabinet space. We’ll recommend a cost-effective controller + modules BOM.

4) Relay output vs transistor output: which should I choose?

Relay outputs are universal for many loads and AC/DC switching. Transistor outputs are recommended for high-speed switching (pulses, fast sensors, motion-related signals). If you’re unsure, tell us your load type and switching frequency.

Smart 200 PLC (Standard & Economical)

5) What is the difference between Smart 200 Standard and Smart 200 Economical PLC?

Standard models focus on broader built-in features and higher configurations, while Economical models are optimized for cost-effective projects. Choose based on I/O requirements, program/data space needs, and expansion/communication options.

6) Do Smart 200 controllers support Ethernet communication?

Many Smart 200 models include an Ethernet port (10/100 Mbps adaptive). If you need distributed I/O over Ethernet, consider PLINK Net IO Header or compatible Ethernet modules depending on your architecture.

7) Can Smart 200 use expansion signal boards (SB)?

Yes. Smart 200 supports expansion signal boards for communication, digital I/O, analog I/O, and temperature acquisition. See the “Smart 200 Expansion Signal Board” page for the full SB model list and configuration references.

8) Can I expand Smart 200 with standard EM expansion modules?

Yes. Smart 200 Standard Expansion Modules (EM series) provide digital, analog, and temperature options. Select the proper EM type in software configuration as shown on the expansion module page.

S7-200 Series Compatible PLC

9) Which S7-200 series compatible CPU should I choose?

Choose based on digital I/O count, whether you need built-in analog I/O, how many RS485 ports you need, and whether you require Ethernet. The “Model Selection Table” on each PLC page is the fastest way to compare.

10) Do you offer CPU models with built-in Ethernet?

Yes. There are CPU variants with Ethernet (ETH). If your project needs remote monitoring, HMI, MES, or PLC-to-PLC communication, Ethernet models are recommended.

Expansion Modules (Digital / Analog / Temperature)

11) How do I choose between digital input and mixed I/O modules?

If you only need sensors/switches, choose DI-only modules. If you need both sensors and outputs in a compact space, choose mixed I/O modules (e.g., 8DI/8DO or 16DI/16DO types).

12) What is the difference between AI, AQ, and AM modules?

AI modules provide analog inputs (from sensors). AQ modules provide analog outputs (to drives/valves). AM modules combine analog inputs and outputs in one unit to save space and simplify wiring.

13) My sensor is 4–20 mA. Which module should I pick?

Choose an analog input module that supports current signals. Some high-density analog input models are “current-only”. Confirm your required channels and signal type (voltage vs current) before ordering.

14) Which temperature module should I choose: PT100, NTC, or Type K?

PT100 (RTD) is recommended for accuracy and stability. NTC (10K, 3950) is cost-effective for multiple points. Type K thermocouple is suitable for higher temperature ranges. Match the module to your sensor type.

Smart DBUS (DM Series) Distributed Remote I/O

15) What is DBUS used for?

DBUS modules are designed for distributed remote I/O acquisition via RS485 (commonly Modbus RTU), allowing you to place I/O near field devices and reduce long cable runs.

16) RS485 wiring: star or daisy-chain?

Use daisy-chain topology for RS485 whenever possible. Keep A/B polarity consistent, and add termination at the first and last device.

17) Why is my Modbus RTU communication unstable?

Common causes include A/B reversal, duplicate slave IDs, baud/parity mismatch, missing termination, poor grounding/shielding, and noisy power supplies. Improve shielding, use twisted pair, and ensure proper termination.

18) Can I mix temperature and analog signals in one DBUS module?

Yes. Some DM models combine NTC with analog inputs or analog outputs. Check each model’s description on the DBUS page.

PLINK (Head + PM Modules)

19) What is the difference between Net IO Header, SB PLINK, and DP PLINK?

Net IO uses Ethernet and supports Smart/1200/1500 client modes and Modbus TCP server mode. SB PLINK is for Smart SR/ST hosts (signal board slot). DP PLINK is for Smart CR/CRs hosts via PORT0. SB/DP are typically short-distance expansion with automatic mapping.

20) Do PLINK systems require PLC programming?

In Smart/1200/1500 client modes, PLINK resource mapping can be automatic without additional PLC programming. In Modbus TCP/RTU scenarios, read/write registers like standard Modbus devices.

21) When should I use Modbus IO Header instead of Net IO Header?

Use Modbus IO Header when your master device only has RS485 (Modbus RTU master). If you have Ethernet available, Net IO Header is recommended for better throughput and integration flexibility.

22) Can I mix Digital, Analog, and Temperature PM modules together?

Yes. Select the header first, then add PM modules based on your required signal types and channel counts. Group modules by function to simplify wiring and maintenance.

Ordering, Shipping & Support

23) Do you provide product manuals and wiring diagrams?

Yes. Manuals and reference documents are available for most product lines. If you need a specific wiring example, tell us your model and application and we will provide a clear reference.

24) How do I confirm I selected the right analog signal type (voltage/current)?

Before ordering, verify your sensor/output specifications (0–10V, ±10V, 4–20mA, 0–20mA, etc.). Then choose modules that explicitly support that signal type. If you share your instrument datasheet, we can confirm the correct module.

25) Can you support OEM/ODM customization?

For volume projects, customization may be possible depending on requirements (labeling, firmware options, packaging, etc.). Contact us with your target model, quantities, and technical requirements.

Still Have Questions?

Send us your application details (PLC model, I/O list, sensors, distance, protocol). We’ll reply with a recommended solution.