Nothing derails an automation project faster than running out of I/O mid-installation. You spec a controller, build the panel, and then discover you're two analog inputs short for that PID loop. The fix—adding a remote I/O module—blows both your BOM and your timeline. That's why a systematic I/O audit before selecting your Coolmay EX3S model pays for itself ten times over.
The EX3S series comes in several I/O configurations, and knowing exactly what each model offers is the first step:
| Model | Digital Inputs | Digital Outputs (Transistor) | Analog Inputs | Analog Outputs | HMI Screen |
|---|---|---|---|---|---|
| EX3S-14MT-4AI2AO | 8 | 6 (NPN) | 4 (0–10 V / 4–20 mA) | 2 (0–10 V) | 4.3″ |
| EX3S-24MT-4AI2AO | 14 | 10 (NPN) | 4 (0–10 V / 4–20 mA) | 2 (0–10 V) | 4.3″ |
| EX3S-32MT-4AI2AO | 18 | 14 (NPN) | 4 (0–10 V / 4–20 mA) | 2 (0–10 V) | 7.0″ |
| EX3S-32MT-8AI4AO | 18 | 14 (NPN) | 8 | 4 | 7.0″ |
A few practical guidelines when counting I/O: tally every field device—every sensor, relay, contactor, transmitter, and positioner—then add 15–20 percent for future modifications. Verify analog range compatibility too; 4–20 mA current loops may need external burden resistors depending on the input configuration. And remember that the COM port on the EX3S can run Modbus RTU without consuming any of the built-in analog channels, so you don't lose I/O when adding serial communication.
For a typical packaging machine with 12 sensors, 4 cylinders, a temperature transmitter, and one analog speed reference to a VFD, the Coolmay EX3S-24MT-4AI2AO fits perfectly with room to spare. If the application demands a larger operator interface or extra I/O headroom, the EX3S-32MT-4AI2AO moves up to a 7.0-inch HMI while keeping the same footprint.
Need help auditing your I/O list? Contact our applications team — we can review your requirements and recommend the right EX3S configuration within 24 hours. Download the full EX3S datasheet for wiring diagrams and detailed I/O mapping tables.
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