Description
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Model | AAI835-H50 |
| Manufacturer | Yokogawa |
| Product Type | Analog I/O module |
| Input Channels | 4 |
| Output Channels | 4 |
| Input Signal | 4–20 mA DC |
| Output Signal | 4–20 mA DC |
| Communication | HART protocol |
| Channel Isolation | Isolated between channels and system |
| Allowable Input Current | 25 mA |
| Input Resistance, Power On | Approximately 290–450 Ω, depending on input current |
| Input Resistance, Power Off | 500 kΩ or greater |
| Input Accuracy | ±16 µA |
| Output Accuracy | ±48 µA |
| Output Load Resistance | 0–750 Ω |
| Data Update Period | 10 ms |
| Transmitter Supply | At least 15.0 V DC at 20 mA; maximum 29.3 V DC at 0 mA |
| Withstand Voltage | 500 V AC for one minute under specified isolation test conditions |
| Power Consumption | 360 mA at 5 V DC; 450 mA at 24 V DC |
| Weight | Approximately 0.2 kg |
| Explosion Protection | Not included in the H50 configuration |
| Temperature Range | Confirm against the applicable installation specification; the standard suffix 0 is not the wide-temperature option |
Specifications are based on Yokogawa AAI835 family documentation. The H50 suffix denotes HART communication, no explosion protection, and the basic configuration. Confirm the exact hardware revision and terminal arrangement before ordering.
Product Introduction
Yokogawa AAI835-H50 HART Analog I/O Module
The Yokogawa AAI835-H50 is an isolated current I/O module for process control systems requiring both analog signal acquisition and analog control output. It provides four 4–20 mA input channels and four 4–20 mA output channels, with HART communication available across the channels for compatible field devices.
AAI835-H50
Its combination of analog control signals and digital instrument communication supports transmitter monitoring, control-valve interfacing, and field-device diagnostics. Channel isolation helps limit signal interaction, but correct system configuration, field wiring, and terminal hardware remain essential to reliable operation.
Application Scenarios & Field Pitfalls
The AAI835-H50 is useful where a control-system node must handle both incoming process measurements and outgoing control signals. A common commissioning problem is treating every 4–20 mA card as interchangeable. This module has a specific four-input/four-output arrangement and HART capability; replacing it with an input-only or output-only card changes the channel allocation and may require control-logic and wiring changes.
Typical applications
- Process measurement: Receives 4–20 mA signals from pressure, flow, level, and temperature transmitters.
- Final control elements: Sends 4–20 mA commands to compatible valve positioners and other current-operated devices.
- Smart instrument maintenance: Supports HART communication for compatible transmitter configuration and diagnostic access.
- Mixed analog I/O cabinets: Combines four measurement inputs and four control outputs in one isolated module.
Engineering checks before installation
- Verify the channel assignment. Confirm which channels are configured as inputs and which are outputs. Do not assume all eight channels have the same direction.
- Check the HART requirement. The
Hsuffix identifies HART support. A standardSversion is not an equivalent choice when digital instrument communication is required. - Confirm the explosion-protection requirement. The
5suffix indicates a configuration without explosion protection. Hazardous-area suitability must be assessed at the complete system and installation level. - Check the terminal and cable interface. The base model does not automatically establish which terminal block or cable adapter is supplied. Options such as
/K4A00and/13S00identify different connection arrangements. - Validate output-loop loading. Check the total loop resistance, including field-device input resistance and cable resistance, against the module’s specified output-load limit.
The suffix and connection-option definitions are documented in Yokogawa’s model-selection information.
Related Products
The following Yokogawa modules belong to related analog I/O families. They are alternatives for specific signal requirements, not automatic replacements for the AAI835-H50.
| Model | Function Difference | Potential Application |
|---|---|---|
| AAI835-H53 | Same 4-input/4-output HART function, with ISA G3 and -20 to 70°C temperature options | Wider-temperature installations |
| AAI835-S50 | Same isolated 4-input/4-output arrangement without HART | Standard analog loops without HART requirements |
| AAI835-S53 | Standard analog I/O version with G3 and wider temperature range | Environmental requirements without HART |
| AAI135-H50 | Eight isolated 4–20 mA inputs with HART; no analog outputs | Transmitter-heavy installations |
| AAI135-S50 | Eight isolated current inputs without HART | Conventional analog measurement |
| AAI143-H | Sixteen-channel isolated 4–20 mA input module with HART | Higher-density measurement systems |
| AAI543-H | Sixteen-channel isolated 4–20 mA output module with HART | Higher-density analog control outputs |
| AAI841-H | Eight inputs and eight outputs, non-isolated, with HART | Applications requiring greater channel density |
These model functions are identified in Yokogawa’s CENTUM I/O documentation. Verify the FCS type, node unit, terminal board, cable, redundancy configuration, and HART requirements before selecting an alternative.
Procurement and compatibility note: The AAI835-H50 base model should not be confused with /K4A00 or other terminal-interface variants. When sourcing a replacement, compare the complete part number, including suffixes and option codes, against the installed module and system engineering records.
