Product Core Brief
- Model: 07KT98, OEM part GJR5253100R0202
- Brand: ABB
- Series: Advant Controller 31 (AC31) high-capacity integrated PLC CPU
- Core Function: Execute large-scale user control logic, process native onboard I/O, operate as CS31 bus master for distributed I/O expansion
- Product Type: DIN rail compact all-in-one PLC central processing unit with integrated field I/O
- Key Specs: 1 MB program Flash storage | Supports up to 31 CS31 remote stations | Dual 50 kHz hardware counters Condition: New Surplus
Product Introduction
ABB 07KT98 is the highest memory integrated CPU in the AC31 90-series lineup, built for large packaging, material handling and medium process skids requiring extensive program logic and distributed I/O.This unit surpasses the 07KT94 model by quadrupling program flash to 1 MB; its dedicated expansion slot accepts external communication processors for Modbus TCP/Profibus DP, while the real-time clock eliminates external timing modules for batch and recipe tracking tasks.
Key Technical Specifications
| Parameter | Value |
|---|---|
| User program storage | 1 MB Flash EPROM, 256 kB data SRAM, 1 MB retain DRAM |
| Base cyclic task scan speed | 0.07 ms per kB of loaded program logic |
| Onboard digital I/O | 24 DI / 16 sinking transistor DO / 8 configurable DI/DO |
| Onboard analog channels | 8 multi-range configurable AI; 4 configurable AO |
| High-speed counter hardware | 2 independent channels, max 50 kHz input frequency, 7 operating modes |
| Serial communication ports | COM1 (programming, ASCII); COM2 (Modbus master/slave, ASCII) |
| Expansion interface | Dedicated slot for external comm processors (07KP90 series) |
| Fieldbus interface | CS31 RS485 master, fixed 187.5 kbps baud rate |
| Max CS31 remote slave count | 31 distributed I/O modules |
| Module operating supply | 24 V DC ± 10 %, total 3.0 W power dissipation |
| Galvanic isolation | Opto-isolation separating field I/O, serial ports and CPU logic |
| Front panel controls | Physical RUN/STOP switch; dedicated bus, I/O and diagnostic status LEDs |
| Mechanical mounting | TS35 standard DIN rail vertical cabinet installation |
| Operating ambient range | 0 °C to +55 °C full rated I/O performance |
| Storage temperature | -25 °C to +75 °C, non-condensing 5–95 % RH |
| Physical dimensions | W120 mm × H140 mm × D85 mm |
| Net unit mass | 0.56 kg |
| System compatibility | All AC31 remote I/O modules; incompatible with AC500 S500 hardware |
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-reference serial numbers against ABB AC31 spare parts databases; inspect terminal spring tension, RUN/STOP switch travel, front LED functionality, and PCB edge connector gold plating for oxidation. Match intact OEM anti-static packaging seals to filter counterfeit surplus stock.
- Live Functional Test: Mount the unit to a DIN rail test bench paired with a bus simulator, calibrated analog signal generators, and 0.5 A resistive output load banks; run continuous 24-hour cyclic program execution with active high-speed counters and simulated remote slave communication. Log stable 24 V supply and CPU temperature with a Fluke 115 multimeter through the full test cycle.
- Electrical Parameter Test: Use a 500 V Megger to measure isolation resistance between all onboard field channels and internal CPU logic; pass threshold set above 10 MΩ. Inject overrange analog signals and channel short circuits to verify built-in fault limiting without CPU lockup.
- Firmware Verification: Read and record factory CPU firmware revision via COM1 programming port; photograph bus termination jumper location and document factory default RUN-mode startup configuration for commissioning reference.
- Final QC & Packaging: Wipe PCB surfaces with anti-static cloth; place the unit in foam-lined static shielding bag, attach a QC Passed label printed with inspection date before sealing in original factory carton.
Replacement Pitfall Guide
❗Firmware Mismatch Risk: Projects written for smaller 07KT94 CPUs exceed memory limits when downloaded to the unit without reconfiguration. Unadjusted memory map allocations trigger constant program overflow faults and immediate CPU halt. Mitigation: Recompile all AC31GRAF project logic targeting this CPU’s 1 MB memory partition before rack installation.❗DIP Switch / Jumper Misconfiguration: The bus termination jumper ships factory-disabled. Un-terminated trunk wiring creates signal reflection noise that drops communication with all remote I/O slaves during large motor starter switching events. Mitigation: Set the internal termination jumper ON if this CPU sits at the physical far end of the bus trunk.❗Terminal / Cable Incompatibility: Compact AC31 CPU terminal cables omit dedicated analog output and counter wiring pins. Forced insertion scratches delicate analog front-end PCB traces. Mitigation: Deploy only OEM full-size terminal cable assemblies matched to the unit’s complete onboard mixed I/O pinout.❗Power Supply Mismatch: A single low-wattage 2 A auxiliary supply cannot feed a DIN rail populated with this CPU plus multiple bus repeaters and comm processors. Combined peak switching draw exceeds the supply continuous rating. Mitigation: Size rack power supplies with 20 % current headroom above total combined CPU and I/O load.❗ESD Damage: Dry workshop air generates static discharge to exposed terminal and serial port traces. Field records show ungrounded handling burns analog input reference circuits, full machine downtime labor costs exceed $1,200. Mitigation: Place an anti-static mat under the DIN rail assembly and hold bare cabinet ground metal for three full seconds before mounting the unit.
Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
Compatibility Matrix
- 07KT98 → 07KT94 : Needs Adaptation — limited 240 kB memory requires heavy program trimming, comm processor expansion slot is absent, all Modbus logic needs rework
- 07KT98 + Remote I/O (07DC92 / 07AI91) : Direct — native bus register mapping, no program edits needed for mixed analog/digital expansion
- 07KT98 + Freelance 2000 DRA02 Rack : Incompatible — RS485 bus does not interface with Freelance internal parallel rack backplane
- 07KT98 + 24 V DC NPN proximity sensors / Pt100 temperature probes : Direct — factory onboard I/O topology matches standard discrete and analog field device wiring
- 07KT98 + AC500 S500 I/O racks : Incompatible — S500 relies on FBP fieldbus instead of legacy protocol
