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Key Technical Specifications
| Parameter | Value |
|---|---|
| Manufacturer | National Instruments |
| Model Number | cFP-AO-200 |
| Product Series | Compact FieldPoint |
| Product Type | Eight-channel current analog output module |
| Mounting Platform | Compact FieldPoint backplane, cFP-BP-x |
| Output Channel Count | 8 single-ended channels |
| Output Ranges | 0–20 mA or 4–20 mA, individually configurable per channel |
| Default Power-Up Output | 0 mA |
| Output Overrange | 0.5 mA |
| DAC Resolution | 12 bits; 1 part in 4,096; approximately 6 µA per bit |
| Typical Absolute Accuracy | 0.1% of full-scale reading |
| Maximum Absolute Accuracy | 0.3% of full-scale reading |
| Output Slew Rate | 0.4 mA/µs |
| Maximum Update Rate | 200 updates/s |
| External Loop Supply | 5–24 V DC |
| Maximum Load Resistance | Up to 1 kΩ at 24 V DC loop supply; up to 100 Ω at 5 V DC loop supply |
| Channel Terminals | Iout output, COM common, Vsup loop-supply terminal |
| Fault Indication | Eight red open-loop LEDs; green POWER and READY LEDs |
| Protection | Short-circuit and open-circuit protection |
| Transient Isolation | 2,300 V RMS transient overvoltage protection between inter-module communication bus and I/O channels |
| Operating Temperature | −40 to +70 °C |
| Weight | 110 g / 3.7 oz |
| Hot Plug Capability | Supported on a powered Compact FieldPoint backplane without disturbing other installed modules or connector blocks |
| Replacement Requirement | Confirm cFP form factor, backplane type, connector block, field loop supply, output range, and application configuration |
The cFP-AO-200 provides eight independently configurable 0–20 mA or 4–20 mA outputs with 12-bit resolution. It requires a 5–24 V DC external loop supply, can drive up to 1 kΩ per output at 24 V DC, includes open-loop detection and short-circuit protection, and operates from −40 to +70 °C.
Product Introduction
National Instruments cFP-AO-200 is an eight-channel current analog-output module for Compact FieldPoint distributed I/O systems. It sources 0–20 mA or 4–20 mA control signals to field devices such as valve positioners, I/P converters, analog-input drives, current-controlled actuators, and process-control equipment.
Each channel is independently configured for 0–20 mA or 4–20 mA operation and uses a 12-bit DAC. The module needs an external 5–24 V DC loop supply, while it receives its operating power from the Compact FieldPoint backplane. Verify loop voltage and load resistance before using it as a replacement.
cFP-AO-200
cFP-AO-200
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to This Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| No POWER or READY indicator | Backplane power missing, cFP backplane fault, module not seated, damaged module | ✅ Medium | Measure the Compact FieldPoint backplane supply at the cFP-BP-x according to NI documentation; reseat the module with site approval; check adjacent modules | Verify backplane power and module seating before replacing cFP-AO-200. |
| All eight outputs read 0 mA | Module not configured, host communications stopped, backplane problem, external loop supply missing | ✅ High | Check the host application and FieldPoint diagnostics; confirm each channel command; measure Vsup-to-COM loop supply at the connector block | The module defaults to 0 mA after power-up. Restore application control and verify external loop supply before replacing hardware. |
| One output channel reports open loop | Broken field conductor, failed final element, missing loop supply, excessive loop resistance, blown external protection | ✅ High | Check the corresponding red open-loop LED; measure Vsup-to-COM; measure continuity from Iout through the field load to COM with power isolated | Repair the field loop first. The cFP-AO-200 specifically detects open current loops. |
| Output command changes but measured current remains 0 mA | Open circuit, no external loop supply, wrong terminal wiring, field device failure | ✅ High | Verify Vsup, COM, and Iout wiring against the diagram; measure loop current with a Fluke 789 or equivalent process meter in series | Correct terminal wiring and field power. Replace the module only if a known-good loop still receives no current. |
| Output cannot reach 20 mA | Loop supply too low, load resistance too high, excessive wiring resistance, field device burden too large | ✅ High | Measure loop supply at Vsup-to-COM under command; calculate allowed load using Rmax=(Vsupply−Vinternal drop)/0.0205R_max=(V_supply-V_internal drop)/0.0205 | Increase loop-supply voltage within the permitted 5–24 V DC range or reduce loop burden. At 24 V DC, the module supports up to 1 kΩ. |
| Output current is inaccurate | Incorrect output range, scaling/configuration error, poor measurement method, damaged channel | ✅ Medium | Confirm whether the channel is configured for 0–20 mA or 4–20 mA; command 4 mA, 12 mA, and 20 mA; measure with a calibrated loop meter | Correct configuration before replacing hardware. Validate the meter and field wiring first. |
| Output is unstable or noisy | Poor shield grounding, loose terminal, unstable external loop supply, load intermittence, host command fluctuations | ✅ Medium | Trend commanded output and measured current; inspect Vsup stability; check shield termination and terminal torque | Determine whether the current source or field loop is unstable. Do not replace the module solely because a valve or actuator hunts. |
| Output channel is shorted | Damaged field cable, failed load, wiring error, water ingress | ✅ High | De-energize and isolate the field circuit; measure resistance between Iout, COM, and ground; inspect for cable damage | Clear the short before reconnecting. The module has short-circuit protection, but repeated faults can cause process downtime. |
| Replacement module is installed but outputs are wrong | Wrong slot mapping, un-restored configuration, channel range mismatch, terminal block wiring error | ✅ High | Confirm slot number in NI MAX and application configuration; compare each channel’s range and wire number against the old installation | Restore configuration and perform a controlled output test before putting final elements back into service. |
❗ Output-range warning: Each channel can be configured for either 0–20 mA or 4–20 mA, and the default power-up state is 0–20 mA with the output at 0 mA. A valve positioner expecting 4–20 mA may interpret 0 mA as a fault or drive toward its configured fail response. Confirm every channel setting before commissioning.
❗ Loop-supply warning: The cFP-AO-200 sources current from an external 5–24 V DC loop supply. It does not create a usable current loop from backplane power alone. Measure Vsup-to-COM at the connector block while the output is commanded active.
❗ Load-resistance warning: Do not assume a 24 V DC loop can drive any load. The module can drive up to 1 kΩ at 24 V DC, while a 5 V DC supply limits the maximum load to 100 Ω. Add cable resistance, intrinsic-safety barriers, isolators, indicators, and field-device burden before deciding the loop is within limits.
❗ Hot-plug warning: The module supports hot plug-and-play on a powered Compact FieldPoint backplane, but that does not make every process loop safe to disturb. Removing an output module can force outputs to 0 mA and move connected equipment. Place outputs in a known safe state and obtain operations approval before removal.
❗ ESD warning: Use a grounded wrist strap and handle the module by its housing. I have watched a technician fix a field short, then place the replacement module on an unprotected cardboard box in dry air. The module powered up but lost one channel during commissioning. Use ESD protection from removal through installation.
Keep these checks in mind and you will save yourself 90% of typical rework time. If you need help, send technical support photos of the cFP-AO-200 label, cFP backplane model, connector block, field wiring, POWER/READY/open-loop LEDs, loop-supply measurement, and NI MAX or application diagnostics.
Frequently Asked Questions
What is the NI cFP-AO-200?
National Instruments cFP-AO-200 is an eight-channel analog current-output module for Compact FieldPoint. It provides individually configurable 0–20 mA or 4–20 mA outputs for field devices and mounts on a Compact FieldPoint cFP-BP-x backplane.
How many output channels does cFP-AO-200 provide?
The cFP-AO-200 provides eight single-ended analog current-output channels. Each channel is independently configurable for 0–20 mA or 4–20 mA operation.
Does cFP-AO-200 output voltage signals?
No. The cFP-AO-200 is a current-output module. Its supported output ranges are 0–20 mA and 4–20 mA. Do not substitute it for a 0–10 V, ±10 V, or other voltage-output module.
This is a common procurement error. A current-output module may physically fit the same Compact FieldPoint platform as another I/O module, but it cannot directly drive a voltage-input device without appropriate signal conversion.
What external power supply does cFP-AO-200 require?
The cFP-AO-200 requires an external DC loop supply between 5 V DC and 24 V DC. The module receives its operating power from the Compact FieldPoint backplane, but the external Vsup-to-COM supply provides the energy needed to source output current through the field load.
At 24 V DC, an output can drive up to 1 kΩ. At 5 V DC, it can drive only up to 100 Ω. Verify all loop burden before installation.
Can I hot-swap the cFP-AO-200?
The cFP-AO-200 supports hot plug-and-play on a powered Compact FieldPoint backplane without disturbing the operation of other installed modules or connector blocks. However, that is a hardware capability, not permission to disturb a live process output.
Before removal, identify every connected final element. An output that drops to 0 mA can close a valve, open a valve, stop a drive, trip a dosing pump, or trigger a bad-input alarm depending on field-device configuration. Use the plant’s approved bypass, manual-control, and maintenance procedure.
Why is an open-loop LED lit on cFP-AO-200?
Each output channel includes open-current-loop monitoring and a red indicator for an open loop. The LED typically points to a broken wire, disconnected field device, missing loop supply, excessive loop burden, open fuse, or wiring error—not automatically a failed output channel.
Start by measuring loop supply between Vsup and COM. Then isolate the loop and check continuity from Iout through the load and back to COM. Do not replace the module until a known-good field loop confirms the channel cannot source current.
Will replacing cFP-AO-200 retain the output configuration?
Do not assume it will. The module’s channel configuration is normally established by the Compact FieldPoint host application and FieldPoint configuration, while the hardware powers up with each channel set for 0–20 mA and output at 0 mA.
Before replacement, save the project configuration and document:
- Backplane position and module slot
- Channel-to-loop mapping
- Required 0–20 mA or 4–20 mA range for each channel
- Normal operating output values
- Field device type and fail action
- External loop-supply voltage and wiring arrangement
After replacement, command and measure each channel at 4 mA, 12 mA, and 20 mA under an approved commissioning procedure.
Is cFP-AO-200 obsolete, and why is New Surplus stock cheaper?
Compact FieldPoint is legacy NI hardware, so cFP-AO-200 supply typically comes from New Surplus, refurbished, or used-tested inventory. New Surplus hardware often originates from cancelled projects, unused plant spares, distributor overstock, or laboratory inventory releases. The price can be lower because it is sourced outside current factory production.
For a New Original / New Surplus unit, request actual photos of the product label, connector edge, housing, and packaging; confirmation of condition; hardware revision if visible; warranty and return terms; confirmed quantity; and actual dispatch lead time.
What testing should a supplier complete before shipping?
A supplier should complete a traceable test process:
- Inbound inspection and traceability: Verify the NI model label, serial number, factory markings, source documentation, and packaging. Inspect for corrosion, altered labels, cracked housing, bent connector contacts, heat discoloration, rework marks, and damaged terminals.
- Backplane fit test: Install the cFP-AO-200 in a compatible Compact FieldPoint cFP-BP-x backplane. Confirm correct seating, normal POWER and READY indicators, and stable module recognition.
- Live functional test: Supply a regulated 5–24 V DC external loop source. Configure each channel for the correct range, then command 0 mA, 4 mA, 8 mA, 12 mA, 16 mA, and 20 mA as applicable. Measure output with a calibrated Fluke 789 process meter or equivalent.
- Open-loop and short-circuit tests: Confirm that each channel reports an intentional open loop correctly. Test short-circuit protection using an OEM-approved controlled fixture; never use uncontrolled live shorts on the module.
- Load and thermal test: Run all eight channels into representative resistive loads within the permitted burden limit for more than 24 hours where the test bench permits. Monitor output stability, LED status, current drift, backplane communication, and temperature.
- Configuration verification: Record the test backplane slot, channel range, loop-supply voltage, firmware or hardware revision where available, and measured output values. Photograph the label and connector condition.
- Final QC and packaging: Obtain QC sign-off, use anti-static packaging, protect the connector edge, add bubble wrap and heavy-duty corrugated boxing, and apply a dated QC-passed label. Test photos and the test report should be available upon request.
