ABB 07KR31 central processing unit

Description

07KR31

What hooks me on the ABB 07KR31 every time is that straightforward muscle: the EEPROM holds your 2K words of user memory like a vault, so program tweaks survive power dips without a sweat, and those opto-isolated inputs shrug off the noise from nearby VFDs. The relay outputs pack 2A punch at 250VAC, driving contactors without the heat buildup you get from solid-state knockoffs, and that programmable RS232? Gold for hooking up a handheld HMI on the fly. It’s got just enough expandability via the system bus for chaining I/O slaves, making redundancy a breeze in safety loops—I’ve layered it with 07KT expansions for SIL-rated sequences that run cooler than a Honeywell equivalent.

Here’s the meat-and-potatoes specs I’ve leaned on in the field for this 07KR31:

• Power Supply: 24 VDC nominal (isolated, short-circuit protected)
• User Memory: 2 K words (EEPROM, non-volatile)
• Binary Inputs: 12 (24 VDC, opto-isolated, 5 ms response)
• Binary Outputs: 8 relay contacts (2 A / 250 VAC max)
• Communication: RS232 programmable port, RS485 system bus
• Operating Temperature: 0°C to 55°C
• Power Consumption: 10 VA typical
• Dimensions: 120 x 70 x 100 mm (0.6 kg)

This bad boy thrives in those gritty, spread-out processes—think pulp and paper lines, pharmaceutical batching, or even light assembly where you’ve got discrete sensors and actuators scattered across a floor, all talking back to a central brain without Ethernet sprawl. ABB tuned the CS31 for exactly those spots: decentralized enough to dodge single-point failures, but centralized where it counts for quick logic tweaks.

Fair warning, though—the ABB 07KR31‘s RS485 can get chatty if you overload the bus with too many nodes; I’ve chased echo errors by dropping terminators in wrong spots more than once, so map your chain meticulously. And while the relays are beasts, they click like castanets in quiet rooms—noise spec it out if you’re in audio-sensitive zones. EEPROM writes take a hair longer than flash these days, too; budget extra for commissioning if you’re green on ABB tools.

All said, if you’re piecing together a CS31 island on a shoestring and need a CPU that won’t quit, snag the 07KR31—it’s cheaper than ripping in a full DCS and twice as forgiving in the dirt. In my book, it’s the pick over flashier micros for anything under 50 I/O points; pair it right, and it’ll clock decades without a burp. Just keep that firmware patched—legacy or not, ABB’s still dropping updates that iron out the oddball hangs.

Detailed Technical Specifications