Allen-Bradley 1797-OB4D Digital Output Modules
Configured for discrete actuator driving and field loop switching in hazardous location FLEX Ex platforms, the Allen-Bradley 1797-OB4D (1797-OB4D FLEX Ex Digital Output Module) provides direct physical/electrical execution.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 1797-OB4D |
| Brand | Allen-Bradley |
| Origin | USA |
| Weight | 0.60 lbs |
| Dimensions | Standard FLEX Ex module footprint |
| Operating Temp | -20 deg C to 70 deg C |
| Power Consumption | 24 VDC backplane bus power |
| Output Count | 4 non-isolated sourcing outputs |
| Terminal Interface | 16-pin terminal base interface |
| Circuit Protection | Short-circuit and open-load diagnostics |
| System Platform | FLEX Ex (1797 Series) |
Deterministic Network Backplane and Interface Performance
Designed to interface directly with intrinsically safe solenoid valves and indicator loops, the module executes discrete logic commands received over the FLEX Ex backplane bus. High-speed optocoupler arrays isolate internal bus logic from field circuit transients, while onboard current-limiting components ensure safe energy levels during field line faults. Internal diagnostic detection logic continuously samples channel continuity, logging open-load or short-circuit fault states to upper-level controller memory tags without introducing backplane latency.
Frequently Asked Questions
Q: Does the 1797-OB4D require a dedicated terminal base for field wiring connections?
A: Yes, the module plugs into a compatible 16-pin FLEX Ex terminal base assembly, allowing live insertion and removal of the active module card without disconnecting field wiring.
Q: How does the module handle output short-circuit conditions on a field channel?
A: Upon detecting an overcurrent condition, the affected channel automatically limits current flow and sets a diagnostic fault bit on the backplane bus while maintaining execution on remaining channels.
Q: Can non-IS standard FLEX I/O power supplies be used with the 1797-OB4D module?
A: No, the 1797-OB4D must strictly draw system power from a certified FLEX Ex power supply module (such as the 1797-PS series) to maintain intrinsic safety ratings.
Field Installation Guidelines
Align the module card with the card guides of the 16-pin FLEX Ex terminal base and press firmly until the locking latch engages fully. Ensure field wiring conductors are routed through intrinsically safe wireways, maintaining a minimum physical separation of 50 mm from non-intrinsically safe AC or DC power cables. Connect the terminal base shield ground connector directly to the panel earth bus bar using a low-impedance copper strap to prevent electromagnetic interference from degrading diagnostic detection accuracy.
Allen-Bradley 1797-OB4D Digital Output Modules
Allen-Bradley 1797-OB4D Digital Output Modules
Configured for discrete actuator driving and field loop switching in hazardous location FLEX Ex platforms, the Allen-Bradley 1797-OB4D (1797-OB4D FLEX Ex Digital Output Module) provides direct physical/electrical execution.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 1797-OB4D |
| Brand | Allen-Bradley |
| Origin | USA |
| Weight | 0.60 lbs |
| Dimensions | Standard FLEX Ex module footprint |
| Operating Temp | -20 deg C to 70 deg C |
| Power Consumption | 24 VDC backplane bus power |
| Output Count | 4 non-isolated sourcing outputs |
| Terminal Interface | 16-pin terminal base interface |
| Circuit Protection | Short-circuit and open-load diagnostics |
| System Platform | FLEX Ex (1797 Series) |
Deterministic Network Backplane and Interface Performance
Designed to interface directly with intrinsically safe solenoid valves and indicator loops, the module executes discrete logic commands received over the FLEX Ex backplane bus. High-speed optocoupler arrays isolate internal bus logic from field circuit transients, while onboard current-limiting components ensure safe energy levels during field line faults. Internal diagnostic detection logic continuously samples channel continuity, logging open-load or short-circuit fault states to upper-level controller memory tags without introducing backplane latency.
Frequently Asked Questions
Q: Does the 1797-OB4D require a dedicated terminal base for field wiring connections?
A: Yes, the module plugs into a compatible 16-pin FLEX Ex terminal base assembly, allowing live insertion and removal of the active module card without disconnecting field wiring.
Q: How does the module handle output short-circuit conditions on a field channel?
A: Upon detecting an overcurrent condition, the affected channel automatically limits current flow and sets a diagnostic fault bit on the backplane bus while maintaining execution on remaining channels.
Q: Can non-IS standard FLEX I/O power supplies be used with the 1797-OB4D module?
A: No, the 1797-OB4D must strictly draw system power from a certified FLEX Ex power supply module (such as the 1797-PS series) to maintain intrinsic safety ratings.
Field Installation Guidelines
Align the module card with the card guides of the 16-pin FLEX Ex terminal base and press firmly until the locking latch engages fully. Ensure field wiring conductors are routed through intrinsically safe wireways, maintaining a minimum physical separation of 50 mm from non-intrinsically safe AC or DC power cables. Connect the terminal base shield ground connector directly to the panel earth bus bar using a low-impedance copper strap to prevent electromagnetic interference from degrading diagnostic detection accuracy.
