1746-OB32 — SLC 500 32-Point 24V DC Sourcing Output Module

The 1746-OB32 is a 32-point sourcing (24V DC) output module for the SLC 500 modular chassis, organized into two groups of 16 points with separate commons per group. Each point sources up to 0.5A at 30°C ambient (0.25A at 60°C), with a total module rating of 8A across all 32 outputs combined. It covers high-density, low-current 24V DC switching for pilot lamps, solenoid valves, small contactor coils, and similar field devices that don't need the voltage flexibility of a relay module.

Specifications

Parameter	Value
Part Number	1746-OB32
Output Points	32
Output Type	Sourcing, 24V DC
Operating Voltage Range	5–50V DC
Current per Point	0.5 A (at 30°C), 0.25 A (at 60°C)
Total Module Current	8 A
Output Groups	2 × 16 points, separate commons
Backplane Current (5V)	190 mA
Operating Temperature	0°C to 60°C

High-Density Sourcing Outputs Without Built-In Overload Protection

At 32 points per slot, this module covers a substantial output count without consuming multiple chassis slots — a practical advantage in older SLC 500 panels with limited chassis capacity. The tradeoff is that the standard 1746-OB32 has no internal short-circuit or overload protection circuitry; a wiring fault on one output can stress or damage that point without the module automatically isolating the fault. External fusing per common or per circuit is the standard mitigation, and for installations where overload protection at the module level is preferred, the electronically protected variant of this module family is the appropriate substitute.

The sourcing output convention means devices not compatible with direct DC switching — AC solenoids, AC pilot lights — can still be driven through interposing relays: a 24V DC relay coil connects to the output point, and the relay's contacts switch the AC circuit independently. This is also a common technique for adding electrical isolation in older panels with significant electrical noise on the field wiring.

FAQ

Q: Does this module include short-circuit or overload protection?

No. The standard 1746-OB32 has no internal overload protection — external fusing per circuit or common is recommended, and an electronically protected variant is available for applications where this protection is required at the module level.

Q: Can AC loads be switched using this DC output module?

Not directly. AC loads require an interposing relay: wire the relay coil to the DC output point, then use the relay's contacts to switch the AC circuit independently.

Q: What is the total current limit per common group?

Each group of 16 points shares a common rated for a defined maximum current — keep the simultaneous load on each group's common within its rated limit, separate from the 8A total module figure.

Q: Can this module be installed in any slot of the SLC 500 chassis?

It can be installed in any available I/O slot except slot 0, which is reserved for the processor in modular SLC 500 systems.

1746-OB32 New Sealed 1746OB32 SER D SLC 500 PLC Output Module