PLC controller with fieldbus remote I/O (CANopen, Modbus and EtherCAT couplers)
Distributed control · CANopen, Modbus and EtherCAT bus couplers, node counts and data rates, remote I/O station sizing
A PLC controller with fieldbus remote I/O splits the system in two: a controller module runs the program, and bus couplers with plug-on I/O modules sit near the sensors and actuators, linked back over CANopen, Modbus or EtherCAT. Ask three things first: which fieldbus the controller masters and at what data rate, how many nodes and I/O points each station must carry, and what supply, temperature and protection the stations are rated for.
Controller modules supplied with bus couplers and remote I/O terminal modules, where I/O stations sit away from the CPU on CANopen, Modbus or EtherCAT. CPU selection, local expansion, 24 V budgeting and certification of compact and modular PLCs are covered on the Programmable logic controller page. Industrial PCs, HMIs and stand-alone protocol gateways are outside this page.
CNFX editorial research · Sources checked October 12, 2026 · 5 sources
Choose the fieldbus by node count, data rate and cycle time
CAN in Automation (CiA) states that CANopen CC uses a data link layer according to ISO 11898-1, assumes a physical layer according to ISO 11898-2, and that its bit timing in CiA 301 allows data rates from 10 kbit/s to 1000 kbit/s. [1] Shenyang Vhandy's GCAN-IO-8000 CANopen coupler lists node numbers 1–127 and baud rates of 10–1000 kbps; its GCAN-IO-8100 Modbus coupler lists node numbers 1–247 and 600 bps to 115200 bps. [3]
Editorial calculation: at their top listed rates the CANopen coupler runs 1000 kbit/s and the Modbus coupler 115.2 kbit/s, a ratio of 1000 ÷ 115.2 ≈ 8.7. The Modbus coupler accepts more node addresses (247 against 127) but at a lower bit rate. [3]
The EtherCAT Technology Group (ETG) says EtherCAT, disclosed in IEC 61158, was developed for short cycle times (≤ 100 µs), low jitter for synchronization (≤ 1 µs) and low hardware costs. With full duplex, ETG puts the effective data rate above 90% and the theoretical rate above 100 Mbit/s. Its distributed clocks keep node clocks within much less than 1 µs, shown on a test network of 300 nodes and 120 m of cable. [2]
ETG also notes that only the MainDevice may actively send a frame in a segment while SubDevices forward it, and that TCP/IP can be tunnelled through a mailbox channel without affecting real-time data. [2] Editorial note: if the remote stations carry servo axes or need simultaneous outputs, ask whether the controller is an EtherCAT MainDevice with distributed clock support rather than a CANopen or Modbus master.
Give the supplier the fieldbus, data rate, number of stations, distance between stations, I/O points per station, update time required, and whether motion axes share the bus.
02
Size each remote I/O station
Vhandy describes a complete GCAN node as a bus coupler, 1 to 32 I/O modules and a terminal module, and lists for both couplers a 24 V DC supply (18–36 V), up to 32 plug-in I/O modules (at most 32 × 8 I/O points), a 100 × 69 × 48 mm body, −40 to +85 °C, 0–90% RH without condensation, and IP20. [3]
The CANopen coupler is listed as a standard CANopen slave with 4 TPDO, 4 RPDO, 1 SDO, an emergency object and node error control, with automatic configuration and baud rate set over RS-232. [3]
On the controller side, Vhandy's GCAN-PLC main control module takes up to 32 I/O modules (32 × 8 = 256 channels), offers CAN, Ethernet and RS232/485 interfaces with CANopen, Modbus RTU and Modbus TCP as master or slave, and is programmed in the five IEC 61131-3 languages (SFC, LD, FBD, ST, IL) through OpenPCS. GCAN-PLC-400 is listed with 168M CPU frequency, 16M program storage and 512K data storage; GCAN-PLC-510 and -511 with 400M CPU frequency. [4]
Editorial note: an IP20 station needs a cabinet or enclosure at the machine; specify that enclosure and its rating separately from the PLC.
03
Mochuan MV-series PLCs and Vhandy GCAN controllers with CANopen and Modbus couplers
Wuxi Mochuan lists MV2U, MV3U and MV5U PLC series with 12/08, 16/16 and 32/32 main units, special function modules such as analog, pulse and I/O modules, and a stand-alone RS485 temperature control PLC. [5] Shenyang Vhandy lists GCAN-PLC controller modules programmed through OpenPCS with digital and analog I/O modules, and CANopen and Modbus couplers. [4][3]
Ask each supplier which bus the controller masters, the published coupler limits, and whether the I/O modules on the remote station are the same family as those on the controller.
04
Controller module, bus coupler, plug-in I/O, terminal module and 24 V supply
Part
Role
Fix in the order
Controller (main control) module
Runs the IEC 61131-3 program; masters the fieldbus. [4]
Feeds controller and stations; 18–36 V input on one coupler range. [3]
Supply rating per station.
05
Supply voltage, I/O points per station, memory and bus cycle for a PLC with remote I/O
Scan time depends on your program and I/O count; the only cycle figure in the sources is the EtherCAT target of 100 µs or less, so ask for scan and bus cycle at your configuration. [2]
2 companies list this product among what they make. Company figures are quoted from each
company's own website; every card states where the relationship came from.
Shenyang Vhandy Technology Co., Ltd.
Manufacturing site to be confirmed for the order
Lists GCAN-PLC controller modules with CAN, Ethernet and RS232/485, and CANopen and Modbus I/O couplers with plug-in I/O modules.
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What data rates does CANopen support?
CiA states that the bit timing in CiA 301 allows 10 kbit/s to 1000 kbit/s. [1]
How many I/O points fit on one remote station?
One Chinese coupler range lists up to 32 plug-in modules, at most 32 × 8 I/O points, per coupler. [3]
What cycle time is EtherCAT designed for?
ETG lists cycle times of 100 µs or less and jitter of 1 µs or less as design goals. [2]
Sources and what still needs a direct check
Sources checked 2026-10-12. CiA and ETG are the user and manufacturer organisations behind CANopen and EtherCAT; Shenyang Vhandy and Wuxi Mochuan are makers describing their own controllers, couplers and modules.
