Schneider ACE949-2 Retrofit-Ready Modbus RS485 Card for Altivar Control Systems
The Schneider Electric ACE949-2 is a Modbus RS485 communication option card engineered for seamless integration into Altivar variable speed drive platforms, including the widely deployed ATV31 and ATV71 series. As legacy drive communication infrastructure ages and original option cards reach end-of-life, the ACE949-2 provides a verified, drop-in retrofit path that preserves existing network topology, minimizes rewiring, and restores full Modbus RTU communication capability without requiring a full drive replacement.
For system integrators and maintenance engineers managing aging automation lines, the ACE949-2 addresses one of the most common retrofit challenges: restoring RS485 Modbus communication to a functioning drive whose original communication card has failed, become obsolete, or is no longer available through standard distribution channels. Rather than replacing the entire ATV31 or ATV71 drive — a costly and time-consuming intervention — the ACE949-2 allows the drive to remain in service while re-establishing the communication link to the supervisory PLC or SCADA system.
Upgrade Compatibility Table
| Parameter | Details |
|---|---|
| Compatible Drive Series | Altivar ATV31, ATV71 (option slot required) |
| Communication Protocol | Modbus RTU / RS485 (2-wire) |
| Connector Interface | RJ45 (Modbus network port) |
| Installation Method | Plug-in option card slot on drive front face |
| Baud Rate Support | 4800 / 9600 / 19200 / 38400 bps |
| Replaces / Substitutes | ACE949-2 (direct), legacy Altivar RS485 option cards |
| PLC Compatibility | Modicon M340, M580, Premium, Quantum; third-party Modbus masters |
| HMI Compatibility | Magelis XBTGT, XBTGK series; any Modbus RTU HMI panel |
| Commissioning Tool | SoMove software, drive front keypad (ATV31/ATV71) |
| Retrofit Complexity | Low — no drive firmware change required in most cases |
| Warranty | 12 Months from date of shipment |
Retrofit Planning for Existing Automation Systems
A successful ACE949-2 retrofit begins well before the card arrives on site. Engineers should audit the existing RS485 network segment to confirm bus termination resistors are correctly placed, cable shielding is grounded at one end only, and the total network stub length is within Modbus RS485 specification. In multi-drop installations where the ATV31 or ATV71 shares a bus with other nodes — such as a Modicon TM221 logic controller, a Magelis XBTGT touchscreen HMI, or additional Altivar drives — the node address and baud rate of the replacement card must be configured to match the original card’s settings exactly before the drive is returned to service.
When the control cabinet also houses a Schneider Electric TeSys D contactor assembly or a Zelio Logic smart relay managing auxiliary functions, the retrofit window should be used to inspect terminal block wiring on the TB1 and TB2 strips for corrosion or loose ferrules. The ACE949-2 card itself connects via the drive’s dedicated option slot and draws power internally from the drive’s 24 VDC logic supply — no external power wiring is required. However, if the drive’s internal 24 V supply is shared with an external I/O expansion module such as a VW3A3202 digital I/O extension card, the total current budget must be verified before commissioning.
For sites running a Modicon M340 or M580 PLC as the Modbus master, the Unity Pro or EcoStruxure Control Expert project should be reviewed to confirm the drive’s Modbus slave address, function codes in use (typically FC03 Read Holding Registers and FC06 Write Single Register), and polling cycle time. If the original ACE949-2 was configured with a non-default address or baud rate, these parameters must be restored via the ATV31 or ATV71 keypad menu (COM- group) or through SoMove software connected via the drive’s RJ45 port before the PLC scan cycle is re-enabled. Failure to match these settings will result in communication timeout faults on the PLC side and drive fault F060 or similar communication loss alarms.
Sites that also operate a Schneider Electric Altivar Process ATV630 or ATV930 on the same network should note that those drives use a different option card form factor and are not compatible with the ACE949-2. However, the Modbus RTU protocol layer is identical, so the same PLC function block library can serve both drive families on separate network segments without modification.
Downtime Control During System Migration
Minimizing production downtime during an ACE949-2 swap requires a structured pre-outage preparation sequence. Before isolating the drive, use SoMove or the drive keypad to export or document all parameter settings — particularly the motor control parameters (motor rated voltage, current, frequency, speed), the Modbus communication parameters (slave address, baud rate, parity, stop bits), and any custom fault response configurations. This parameter backup ensures that if the drive requires a factory reset during the card swap, the original configuration can be restored in minutes rather than hours.
During the physical swap, the drive must be fully de-energized and the DC bus voltage verified at zero before the option slot cover is removed. The ACE949-2 card seats into the option slot with a single locking tab — no tools are required. After re-energizing, the communication parameters should be re-entered via the COM- menu before reconnecting the RS485 cable to the network. A loopback test using a Modbus diagnostic tool or the PLC’s communication diagnostic screen confirms that the card is responding correctly before the drive is returned to automatic control mode.
For critical production lines where even a brief communication interruption is unacceptable, a pre-configured spare drive with the ACE949-2 already installed and parameterized can be staged as a hot-swap unit. This approach reduces the actual production outage to the time required for mechanical disconnection and reconnection of the motor and control wiring — typically under 30 minutes for a standard ATV31 or ATV71 installation in a standard control cabinet.
Retrofit Support FAQ
Q1: Is the ACE949-2 a direct drop-in replacement for the original Altivar RS485 communication card?
Yes. The ACE949-2 is the standard Modbus RS485 option card for the ATV31 and ATV71 series and installs directly into the drive’s option slot without any mechanical modification. After installation, communication parameters must be configured via the drive keypad or SoMove software to match the original network settings.
Q2: Will I need to update my PLC program or HMI screens after installing the ACE949-2?
In most cases, no. If the replacement card is configured with the same Modbus slave address, baud rate, and parity as the original, the PLC program and HMI Modbus variable mappings will continue to function without modification. Changes are only required if the original card’s configuration is unknown or if the retrofit is being combined with a broader network upgrade.
Q3: What pre-shipment testing is performed on the ACE949-2?
Each ACE949-2 unit supplied by SMARTNEXMSK undergoes functional verification prior to dispatch, including communication interface continuity checks and visual inspection for connector integrity. Units are shipped in anti-static packaging with a 12-month warranty covering manufacturing defects and communication failures under normal operating conditions.
Q4: Can the ACE949-2 be used in a mixed-protocol cabinet where some drives use Profibus or CANopen?
The ACE949-2 is exclusively a Modbus RS485 card and cannot be used for Profibus DP or CANopen communication. For Profibus connectivity on ATV71 drives, the VW3A3607 Profibus DP option card is the appropriate choice. For CANopen, the VW3A3608 card applies. These cards are not interchangeable with the ACE949-2 and require separate network wiring and PLC configuration.
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