Clients/Buellton/slack/2026/04/2026-04-24_buellton.md

# #buellton — 2026-04-24 **13:22 [Kevin](https://slack.com/archives/C091185E1JN/p1777062157775349):** Plan for Res3 booster change from the SLC 503 to the existing ML1100 This execution plan outlines the conversion of your existing **Digi One IAP** gateway to bridge communications between a **MicroLogix 1100** and two **ABB ACS550 VFDs** via Modbus RS-485. ## **Phase 1: Physical Hardware & Wiring** ### **1.1 Digi One IAP Physical Mode Change** The gateway must be switched from RS-232 (SLC 5/03 mode) to RS-485 2-wire mode. * **DIP Switches:** Locate the 4-position switches on the unit. Set for **RS-485 2-wire** (Standard config: Sw 1: ON, Sw 2: OFF, Sw 3: ON, Sw 4: ON). * **Termination:** Ensure Switch 1 is **ON** to provide end-of-line termination at the gateway. ### **1.2 RS-485 Daisy-Chain Wiring** Since the Digi has one serial port, you will multi-drop both drives. * **Digi Side:** Use the DB9 port (Pins 3/Data+ and 4/Data- are standard for 2-wire 485 on this model). * **ABB ACS550 Side:** Wire to Terminals **28 (B+), 29 (A-), and 30 (AGND)**. * **Topology:** Run the cable from the Digi to VFD #1, then jump from VFD #1 to VFD #2. Enable the termination resistor on VFD #2 only. ## **Phase 2: VFD Parameterization** Configure both ABB drives to listen for Modbus RTU commands. * **9802 (Comm Protocol):** Set to **1 (STD MODBUS)**. * **5302 (Station ID):** Set VFD #1 to **1** and VFD #2 to **2**. * **5303 (Baud Rate):** Set to **19.2k** (or match Digi settings). * **5304 (Parity):** Set to **8 None 1** (or 8 Even 1, provided it is consistent across the bus). * **5305 (Control Profile):** Set to **0 (ABB DRV LIM)** or **2 (DCU PROFILE)** depending on your logic preference. ## **Phase 3: Digi One IAP Configuration** Access the web interface to configure the **Industrial Automation (IAP)** bridging logic. * **Network Side:** Set the Master protocol to **EtherNet/IP**. * **Serial Side:** Set the Slave protocol to **Modbus RTU**. * **Message Routing/Table Mapping:** Create a mapping that translates Allen-Bradley "N" files to Modbus Station IDs. * **Map N10:** To Modbus **Unit ID 1** (VFD #1). * **Map N11:** To Modbus **Unit ID 2** (VFD #2). * **Timing:** Set a modest character timeout (e.g., 50-100ms) to ensure stable RS-485 frames. ## **Phase 4: MicroLogix 1100 Programming** Using RSLogix 500, implement the control logic to talk to the Digi via the Ethernet port. * **MSG Instructions:** Use **SLC Typed Read/Write** instructions. * **Multi-Hop:** Enable Multi-Hop in the MSG setup. * **Hop 1:** IP Address of the Digi One IAP. * **Hop 2:** The routing address that matches your Digi Table Mapping (targeting the correct VFD ID). * **Register Mapping (ACS550):** * **40001:** Control Word (Start/Stop/Reset). * **40002:** Speed Reference (0–20,000 scaling). * **40004/40005:** Status Word and Actual Speed for SCADA feedback. ## **Phase 5: Validation & SCADA Integration** * **Local Control:** Verify that toggling bits in the ML1100 results in the VFDs responding over the 485 link. * **SCADA Independence:** Confirm the SCADA system is successfully polling the ML1100 via its **Serial Port** (Channel 0) without interference from the Ethernet/Digi traffic. * **Error Handling:** Program "Heartbeat" or "Comm Fail" logic in the ML1100 to safely ramp down or stop the VFDs if the Digi or Ethernet link goes offline. **18:18 [Kevin](https://slack.com/archives/C091185E1JN/p1777079906926469):** new plan for the vfd and pressure sensor integration after discussing it with Claude. [[F0AV7EDQGTU_pump_station_remote_io_plan.pdf]]