4 Differential Siemens PLC 6ES7235-0KD22-0XA8 SIEMENS S7-200 CN EM 235 4AI/1AO Analog Module

6ES7235-0KD22-0XA0 is the EM 235 4-input / 1-output analog expansion for S7-200 CN CPUs. It converts 4 differential voltage or current signals into 12-bit digital values and outputs one 12-bit voltage or current set-point--ideal for pumps, valves, temperature loops and small-batch processes without external transmitters.

• 4 AI + 1 AO - differential, isolated channel-to-channel
• 12-bit resolution - 0.1 % accuracy, ±0.2 % full-scale
• Software-selectable ranges - 0-20 mA, 4-20 mA, ±10 V, 0-10 V per channel
• On-board 24 V sensor supply - 60 mA, short-circuit protected
• DIP-switch free - range selection via CPU configuration byte
• Compact size - 71 mm width, fits 35 mm DIN-rail, no fan
• Wide temperature - 0…+55 °C operating, -40…+70 °C storage
• Global approvals - CE, UL 508, CSA, FM Class 1 Div 2, RoHS, REACH

• Small pump VFD speed reference (4-20 mA)
• Tank level transmitter 0-10 V
• HVAC damper position feedback & output
• Packaging machine temperature PID (PT100 -> 4-20 mA)
• Remote I/O for SCADA RTU

• S7-200 CN: CPU 224, 224 XP, 226
• S7-200 SMART: CR40, SR20, ST40 (with DIP adapter)
• Cable: CPU ribbon cable (supplied with CPU)
• Power: 24 VDC 2 A minimum, ripple < 5 %
• Software: STEP 7-Micro/WIN V4.0 SP9 or SMART programming software

1. Snap module onto DIN-rail beside CPU; plug bus ribbon.
2. Wire sensors - use shielded pair, shield earthed at panel entry.
3. Set range byte - CPU configuration table (no DIP switches).
4. Scale values - use Micro/WIN wizard for 4-20 mA = 0-27648.
5. Verify LEDs - green "SF" off, analog values stable in status table.