Field Engineer’s Notes (From the Trenches)
The “Gotcha” is Battery Replacement, Store to Flash & Ethernet IP Planning.
Battery (IC698ACC701): The CPX772 willlose its program if the battery dies AND power is lost. The “BAT LOW” LED illuminates ~30 days before failure.
Rule: Replace the battery with power ON during a scheduled downtime. If you must replace with power OFF, have a laptop with the project file ready to download immediately upon power-up. A “No Config” fault on boot means the RAM cleared.
Mitigation: Perform a “Store Project to Flash” (Target → Store in PME) after major logic changes. This copies the SRAM image to Flash. On next cold start with dead battery, it auto-loads from Flash (status LEDs: MS blinking during load → RUN comes on).
Ethernet Port IPs: All three ports can share the same IP (default) or be assigned different IPs/subnets in PME (CPU Properties → Ethernet Ports). If you separate them, ensure your engineering laptop is on the same subnet as the port you’re connecting to for initial download/programming. Duplicate IPs across ports are allowed (same MAC shared) but if you multi-home, document which port goes to which VLAN/switch.
Backplane Compatibility: The is designed for the RX7i (IC698CHS…) racks with the PCI/VME64 hybrid backplane. It willwork in late-model Series 90-70 racks (IC697CHS771/791) provided the backplane firmware supports PAC protocol extensions, but for guaranteed compatibility in a 90-70-only retrofit, the IC697CPU772 is the native choice. The is primarily an RX7i CPU.
Real-World Applications
- Combined Cycle GT Mark VI Migration (Logic Emulation): A in the Gas Turbine core runs the migrated Speedtronic logic plus the auxiliaries (Lube Oil, Seal Gas, Vent Fan). The 6 MB memory holds the 6,000+ rungs of sequential logic and 3,000 symbolic variables. ETH1 links to the Woodward DSL and the Plant DCS (Modbus TCP) for start permissives; ETH3 exchanges 500 words of EGD with the Balance-of-Plant RX3i. The triple ports avoided adding an ETM001.
- Pharmaceutical Batch Skid (C-Blocks & Strings): The executes custom C-function blocks for batch mass balance and 21 CFR Part 11 audit trail string concatenation. The Pentium III x86 handles the
sprintf()equivalents and floating-point deviation checks in <15ms scan. The embedded Ethernet ports connect directly to the Site-Wide DCS (SRTP) and the Validation Laptop (isolated VLAN on Port 2).
High-Frequency Troubleshooting FAQ
Q: “RUN” LED OFF, “FLT” ON (Solid Red). “BAT LOW” was on last week. Program lost?
A: RAM Cleared (Battery Dead + Power Loss).
- If you performed “Store Project to Flash” previously: Power cycle the rack. The CPU auto-loads from Flash (MS LED blinks during load → RUN comes on in ~30-90 sec). Wait, do not interrupt.
- If noFlash store was done: You must Download the project from Proficy Machine Edition. Connect via Ethernet (or Serial if configured). Target → Connect → Download.
- Prevention: Always “Store to Flash” after major logic changes. Replace the battery (IC698ACC701) with power ON when BAT LOW appears. Keep a spare battery on-site.
Q: CPU is in RUN, but some I/O modules show “Not Responding” or “Config Mismatch”.
A: Hardware Detect Needed or Rack Power Issue.
- Open PME Hardware Config. Right-click the RX7i rack → Detect Hardware. Does it see the modules you physically have? If it detects a mismatch (e.g., you have IC694MDL758 but config says IC694MDL759), update the config to match the physical hardware and re-download.
- Check the Power Supply Module (IC698PSA100 or IC697PWR710 in Slot 0). Is “PWR” LED Green? If the 5V backplane rail sags (overloaded or failing PS), the CPU runs but I/O modules drop off the bus. Measure 5V at the PS test points.
- For Genius/Expander racks: Ensure the BEM731/ETM001 config matches the physical devices and the Bus Terminator is present at the last device.
Q: Cannot connect via Ethernet — “Target Not Found” or “Timeout”.
A: IP Mismatch, Cable, or Port Selection.
- Verify the Ethernet cable (crossover or straight-through — ports are Auto-MDIX). Link LED should illuminate on the port you plugged into.
- Check the IP Address, Subnet Mask, Gateway in PME (Hardware → → Ethernet Port 1/2/3). Is your laptop on the same subnet? (e.g., CPU=10.10.10.50/255.255.255.0, Laptop=10.10.10.100/255.255.255.0). If laptop is on a different subnet, you need a route or change laptop IP temporarily.
- If using Port 2 or 3 for first connection, ensure those ports are configured with valid IPs — by default they may inherit Port 1’s IP or be disabled depending on firmware. For initial commissioning, connect to Port 1 (usually the primary configured port).
- Check Windows Firewall — it may block SRTP (port 18245). Temporarily disable or allow GE SRTP exception.
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