Connect field signals to your PLC or gateway over RS485 Modbus RTU. Choose Y301 for digital I/O, mixed signals and 10 A relay control on ControlLink models, or Y331 for channel-isolated millivolt, voltage, milliamp and ampere inputs.
View Serial I/O Module Documentation
Define the field task first
Describe your signals and load. Then compare the input and output combination that fits your panel.
Read switch, float and equipment status contacts from your controller. Choose a compact input model for a few points, or add relay control when the panel needs both.
Y301-200 · Y301-220 · Y301-440 · Y301-880Compare these models
Use Modbus commands to operate relay contacts. Check the selected model’s contact rating and use an external contactor when the load requires it.
Y301-020 · Y301-110 · Y301-220 · Y301-440Compare these models
Bring analog measurements, digital status and relay control into one module. Choose two or four analog inputs for supported voltage or current signals.
Y301-222 · Y301-444Compare these modelsAcquire DC signals beyond standard 0–10 V and 4–20 mA. Choose 2, 4, 6 or 8 AI channels, each isolated from the other input channels.
0–100 mV · 0–500 mV
0–5 V · 0–10 V · 0–30 V
0–20 mA · 4–20 mA
0–2 A · 0–10 A
Specify the input range when ordering. Connect each signal to its matching voltage or current terminals and keep each channel’s input pair separate.
Default communication: isolated RS485 with Modbus RTU. RS232 and isolated CAN are ordering options. Power: 6–36 VDC; screw mounting.
2 isolated AI · 0 DI / 0 DO / 0 AO
4 isolated AI · 0 DI / 0 DO / 0 AO
6 isolated AI · 0 DI / 0 DO / 0 AO
8 isolated AI · 0 DI / 0 DO / 0 AO
Select the range and channel count together. The 0–10 A option is a DC current input range; these Y331 models have no relay outputs.
Combine digital status monitoring and relay control over RS485 Modbus RTU. ControlLink models provide SPDT relay contacts rated at 277 VAC 10 A or 28 VDC 10 A.
2 DI + 2 relay DO
View Y301-220 Modbus relay module2 DI + 2 relay DO + 2 AI
View Y301-222 Modbus relay module4 DI + 4 relay DO
View Y301-440 Modbus relay module4 DI + 4 relay DO + 4 AI
View Y301-444 Modbus relay module8 DI + 8 relay DO
View Y301-880 Modbus relay moduleY301-222 and Y301-444 also include analog inputs. Match contact voltage, load type, steady current and inrush current before selection. Inductive loads may need protection and an external contactor. MiniLink relay ratings differ.
Built for your control panel
Read inputs and control relay outputs from a compatible RS485 Modbus RTU master.
Pick one or two digital points, expand to eight inputs and eight relay outputs, or combine digital I/O with analog sensing.
Y331 offers millivolt, voltage, milliamp and ampere input ranges, with input channels isolated from one another.
ControlLink models support local relay rules; Y301-222 and Y301-444 also support analog threshold rules.
A Serial I/O module sits between field signals or loads and the PLC, SCADA system, or edge controller that reads and writes its registers.
Y301-444 shown as an example. Cyan: inputs and values to the host. Orange: relay commands to the field load. I/O count and signal support depend on the model.
Signal and load sideConnect compatible inputs to DI or AI, and relay outputs to the selected load circuit.
Module roleThe module exposes field states and values to the host and receives relay commands; it does not replace the controller.
Host sideMatch the interface, protocol mode, baud rate, address, and register map.
MiniLink, ControlLink, and FlexPoint organize the Y301 range by I/O combination and project task.
Compact one- or two-channel digital I/O for status monitoring and relay control.
Y301-110 · Y301-200 · Y301-020
View MiniLink Models
Combined digital input and relay output, with analog input and local rules on selected models.
Y301-220 · Y301-222 · Y301-440 · Y301-444 · Y301-880
View ControlLink Models
Dedicated DI, AI, or AO modules for higher channel counts and signal-specific expansion.
Y301-600 · Y301-800 · Y301-G00 · Y301-006 · Y301-008 · Y301-00G · Y301-0004 · Y301-0006 · Y301-0008
View FlexPoint ModelsFeatured Y301 models
Compare the eight models most often used for digital monitoring, relay control and combined analog sensing.
Need another I/O combination? Compare all 17 Y301 models.
Wiring patterns
Use these three wiring patterns to identify the right product family. Final selection still depends on signal range, load, interface, supply, and installation conditions.
MiniLink or FlexPoint DI models
Need dedicated digital input, analog input or analog output? Open the complete range and compare all 17 models by I/O, power, interface and signal limits.
Includes 9 additional dedicated digital input, analog input and analog output models. Compare the I/O combination, then contact us to confirm model-specific limits before ordering.
Compact one- or two-channel digital I/O for status monitoring and relay control.
Combined digital input and relay output, with analog input and local rules on selected models.
Dedicated DI, AI, or AO modules for higher channel counts and signal-specific expansion.
| Model | I/O | Power | Interface / protocol | Signal or load boundary | Best for | Action |
|---|---|---|---|---|---|---|
| Y301-110 | 1 DI + 1 relay DO | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | SPDT relay · 125 VAC 0.5 A / 30 VDC 2 A | One status input and one relay-control point | |
| Y301-200 | 2 DI | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | Dry / wet contact · 5–36 V wet-contact · opto-isolated | Two-channel status monitoring | |
| Y301-020 | 2 relay DO | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | SPDT relays · 125 VAC 0.5 A / 30 VDC 2 A | Two relay-control points | |
| Y301-220 | 2 DI + 2 relay DO | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | 277 VAC 10 A / 28 VDC 10 A relays · up to 4 local rules | Compact monitoring and relay control | |
| Y301-222 | 2 DI + 2 relay DO + 2 AI | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | 277 VAC 10 A / 28 VDC 10 A relays · 0–10 V / 4–20 mA AI · 16-bit · ±1% FS · up to 4 rules | Mixed digital and sensor monitoring | |
| Y301-440 | 4 DI + 4 relay DO | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | 277 VAC 10 A / 28 VDC 10 A relays · up to 8 local rules | Four-point monitoring and control | |
| Y301-444 | 4 DI + 4 relay DO + 4 AI | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | 277 VAC 10 A / 28 VDC 10 A relays · 0–10 V / 0–5 V / 4–20 mA AI · 16-bit · ±1% FS · up to 8 rules | Mixed four-channel monitoring and control | |
| Y301-880 | 8 DI + 8 relay DO | 5–36 VDC | RS485; optional RS232 / TTL · Modbus RTU | 277 VAC 10 A / 28 VDC 10 A relays · up to 16 local rules | Higher-density digital monitoring and control | |
| Y301-600 | 6 DI | 7–30 VDC | RS485 / RS232 · Modbus RTU / ASCII | Opto-isolated DI · 3.3–24 VDC active input | Six digital status points | |
| Y301-800 | 8 DI | 7–30 VDC | RS485 / RS232 · Modbus RTU / ASCII | Opto-isolated DI · 3.3–24 VDC active input | Eight digital status points | |
| Y301-G00 | 16 DI | 7–30 VDC | RS485 / RS232 · Modbus RTU / ASCII | Opto-isolated DI · 3.3–24 VDC active input | Sixteen digital status points | |
| Y301-006 | 6 AI | 7–30 VDC | RS485 / RS232 · Modbus RTU / ASCII | 0–10 V / 4–20 mA · 12-bit · ±0.5% FS | Six analog measurement points | |
| Y301-008 | 8 AI | 7–30 VDC | RS485 / RS232 · Modbus RTU / ASCII | 0–10 V / 4–20 mA · 12-bit · ±0.5% FS | Eight analog measurement points | |
| Y301-00G | 16 AI | 7–30 VDC | RS485 / RS232 · Modbus RTU / ASCII | 0–10 V / 4–20 mA · 12-bit · ±0.5% FS | Sixteen analog measurement points | |
| Y301-0004 | 4 AO | 12–30 VDC | Isolated RS485; optional RS232 · RTU / ASCII | 0–10 V / 4–20 mA · 14-bit · ±0.1% FS | Four analog setpoint outputs | |
| Y301-0006 | 6 AO | 12–30 VDC | Isolated RS485; optional RS232 · RTU / ASCII | 0–10 V / 4–20 mA · 14-bit · ±0.1% FS | Six analog setpoint outputs | |
| Y301-0008 | 8 AO | 12–30 VDC | Isolated RS485; optional RS232 · RTU / ASCII | 0–10 V / 4–20 mA · 14-bit · ±0.1% FS | Eight analog setpoint outputs |
Need help choosing? Tell us your application.
The correct model depends on the signal, electrical load, host connection, power, environment, and local-control requirement.
Identify each DI, relay DO, AI, or AO point and whether the signal is digital, voltage, or current.
Count the required points and allow only the project margin you can justify.
Verify analog range or relay operating voltage, steady current, inrush current, and load type.
Check RS485, RS232, or TTL availability and the required Modbus mode for the selected model.
Note supply voltage, temperature, humidity, enclosure, wiring, and installation clearance.
Confirm whether local rules, retention, converters, termination, protection, or external contactors are required.
Ready for the next step?
Check signal limits, terminal wiring and Modbus registers for the selected model before final design or ordering.
Questions that change model selection. Check the product family, signal type, communication option, load, and required documents before final selection.
Y301-220, Y301-222, Y301-440, Y301-444 and Y301-880 provide RS485 Modbus RTU and SPDT relay contacts rated at 277 VAC 10 A or 28 VDC 10 A. The rating does not apply to every Y301 model. Verify load type, inrush current and protection requirements; an external contactor may be needed.
Y331-0020/0040/0060/0080 offers millivolt, voltage, milliamp and ampere input range options. Each input channel is isolated from the other input channels. Choose the range when ordering and use the corresponding voltage or current terminals. Mixed ranges and switching between ranges require confirmation for the ordered configuration. The 0–10 A range measures DC current; these models have no relay outputs.
Choose Y301 for digital inputs, relay control, mixed I/O or dedicated DI, AI and AO expansion. Choose Y331-0020/0040/0060/0080 for 2, 4, 6 or 8 isolated analog inputs with millivolt, voltage, milliamp or ampere range options. Compare the signal range and electrical limits before choosing the channel count.
Use DI for discrete status signals, relay DO for on/off load control, AI for supported voltage or current measurements, and AO for supported voltage or current setpoints. Verify signal range, common wiring, isolation, accuracy, and load requirements in the selected model specification.
RS485 Modbus RTU is available across the documented Y301 family and is the default interface for these Y331 analog input models. Y331 also offers RS232 or isolated CAN interface options; specify the interface when ordering. RS232, TTL, and Modbus ASCII are available only on selected models. Set the host interface, protocol mode, baud rate, address, and register map for the selected model.
Do not select a relay from steady current alone. Check operating voltage, inrush current, switching frequency, and load type. Y301-110 and Y301-020 are rated at 125 VAC 0.5 A or 30 VDC 2 A. The featured ControlLink models are rated at 277 VAC 10 A or 28 VDC 10 A. Inductive loads may require protection and an external contactor.
Share the I/O type and channel count, signal range or load, host interface and protocol, supply voltage, installation environment, and any local rule requirement. Submit the conditions you know; missing details can be filled in later.
Open the detailed comparison above and follow the selected model specification for electrical and mechanical limits. Use the linked technical reference for wiring, configuration, communication settings, and register information.
Yes. Open the full model comparison for dedicated 6-, 8-, or 16-channel digital input modules, 6-, 8-, or 16-channel analog input modules, and 4-, 6-, or 8-channel analog output modules. Their supply ranges and signal specifications differ from the featured models.
What do you need to monitor or control? Tell us about your signals and controller. We’ll help you choose a suitable Y301 or Y331 model — no model number needed.
