ABB TB807 3BSE008538R1 Retrofit-Ready Modulebus Terminator for AC800M Control Systems
The ABB TB807 (3BSE008538R1) is a Modulebus Terminator designed for use within the ABB AC800M Distributed Control System platform. As legacy AC800M installations approach end-of-life or require expansion, the TB807 plays a critical role in maintaining signal integrity across the Modulebus backplane. Whether you are replacing a failed unit, upgrading a control cabinet, or migrating from an older S800 I/O configuration, the TB807 ensures proper bus termination and prevents reflection errors that can disrupt real-time process control.
Our stock of the TB807 3BSE008538R1 is sourced from verified industrial supply channels, function-tested prior to dispatch, and backed by a 12-month warranty. Units are available for immediate shipment to support planned turnarounds and emergency maintenance scenarios alike.
Upgrade Compatibility Table
| Parameter | Details |
|---|---|
| Part Number | TB807 / 3BSE008538R1 |
| Manufacturer | ABB (Germany) |
| Function | Modulebus Terminator — terminates the Modulebus on the last module in an AC800M rack |
| Compatible Platform | ABB AC800M DCS (PM861, PM864, PM866 controllers) |
| Compatible I/O Series | S800 I/O modules (AI810, AO810, DI810, DO810, etc.) |
| Backplane Interface | Modulebus (proprietary ABB backplane bus) |
| Installation Requirement | Installed at the rightmost slot of the TB807-compatible rack; no DIP switch configuration required |
| Communication Compatibility | PROFIBUS DP, Modulebus, Foundation Fieldbus (via CI854 / CI857 interface modules) |
| Replacement Recommendation | Direct drop-in replacement for existing TB807 units; no firmware update required |
| Commissioning Notes | Verify rack slot assignment and confirm Modulebus scan in Control Builder M after installation |
| Warranty | 12 months from date of shipment |
Retrofit Planning for Existing Automation Systems
When planning a retrofit or upgrade of an AC800M-based control system, the TB807 is rarely replaced in isolation. A complete modernization project typically involves reviewing the entire rack assembly. The TB807 terminates the Modulebus on the last populated slot of the rack, so engineers must first confirm the rack configuration — whether using a TB810 or TB811 baseplate — and verify that all S800 I/O modules are correctly seated before installing the terminator.
In systems where the PM864 or PM866 controller module is being retained during a partial upgrade, the TB807 must remain in place to prevent bus errors. If the controller itself is being replaced — for example, migrating from a PM861A to a PM864A — the Modulebus topology should be re-validated using ABB’s Control Builder M software to confirm that all module addresses are correctly assigned and that no address conflicts exist on the backplane.
For projects involving communication protocol migration — such as moving from PROFIBUS DP to PROFINET or integrating a CI854A PROFIBUS interface module — the TB807 continues to serve its termination function regardless of the fieldbus layer above it. Engineers should also account for the CI857 FOUNDATION Fieldbus HSE linking device if the site uses FF instrumentation, as the Modulebus termination must be intact for the CI857 to communicate reliably with the controller.
Power supply capacity is a key consideration during any rack upgrade. The SD821 or SD822 power supply modules feeding the S800 I/O rack must be verified against the total current draw of all installed I/O modules. Adding new AI810 analog input modules or DO810 digital output modules increases the load, and the TB807 installation should be the final step after the power budget has been confirmed. Terminal wiring on the TB820 or TB825 I/O terminal units should also be inspected for correct shielding and grounding before commissioning.
For HMI integration, sites running ABB 800xA or third-party SCADA systems connected via OPC DA/UA should verify that the graphic faceplates and tag assignments remain valid after any module replacement. A Modulebus scan initiated from Control Builder M will confirm that the TB807 is correctly recognized and that all downstream I/O modules report healthy status before the system is returned to automatic control.
Downtime Control During System Migration
Minimizing unplanned downtime is the primary concern during any AC800M retrofit. The TB807 3BSE008538R1 is a passive terminator with no firmware or configuration stored on the module itself, which means replacement can be completed without modifying the controller program or downloading a new application. This significantly reduces the risk window during a live system intervention.
Best practice is to perform the TB807 swap during a scheduled maintenance window. Before removing the existing terminator, confirm that the controller is in manual mode and that all critical process outputs are held at safe values. After installing the replacement TB807, perform a Modulebus health check in Control Builder M and verify that all S800 I/O modules — including any AI810, AO810V, DI810, or DO810 units — report online status before returning the controller to automatic mode.
For sites where a cold swap is not feasible, a hot-standby AC800M configuration using redundant PM864A controllers can allow the Modulebus rack to be serviced while the redundant controller maintains process control. In this scenario, the TB807 replacement on the non-active rack can be completed without interrupting the control loop, provided the redundancy switchover has been tested and confirmed prior to the maintenance activity.
All units supplied by SMARTNEXMSK are function-tested and include a pre-shipment inspection report. This reduces on-site commissioning time and provides documented evidence of module health for quality records and audit trails.
Retrofit Support FAQ
Q1: Is the TB807 3BSE008538R1 a direct replacement for my existing TB807 unit?
Yes. The TB807 3BSE008538R1 is the standard ABB part number for the Modulebus Terminator used in AC800M racks. It is a direct drop-in replacement requiring no configuration changes, firmware updates, or program modifications. Simply remove the failed unit and install the replacement in the same rack slot.
Q2: What wiring or terminal changes are required when replacing the TB807?
The TB807 is a backplane-mounted terminator with no field wiring connections. It plugs directly into the Modulebus backplane slot at the end of the rack. No terminal rewiring is required. Ensure the rack power is confirmed stable via the SD821/SD822 supply before installation.
Q3: How do I verify compatibility with my AC800M system version?
The TB807 3BSE008538R1 is compatible with all AC800M rack configurations using TB810 or TB811 baseplates and S800 I/O modules. Compatibility is not dependent on the controller firmware version. After installation, use Control Builder M to perform a Modulebus scan and confirm all modules are recognized. If using a CI854A or CI857 communication interface, verify that the fieldbus link status is healthy after the scan.
Q4: What does the 12-month warranty cover, and what pre-shipment testing is performed?
All TB807 3BSE008538R1 units supplied by SMARTNEXMSK are function-tested prior to dispatch. The 12-month warranty covers manufacturing defects and functional failures under normal operating conditions. Each unit ships with a pre-shipment inspection record. In the event of a warranty claim, SMARTNEXMSK will arrange replacement or repair at no additional cost to the customer.
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