Siemens PLC V90 Servo 111 Telegram Function Block Guide
In modern industrial automation, precise motion control is essential for applications like packaging, material handling, and CNC machinery. The Siemens SINAMICS V90 servo drive, combined with a SIMATIC PLC, offers a cost-effective and high-performance solution. This article dives into the 111 telegram function block, a standard PROFIdrive message type used for speed control with setpoint and actual value exchange. You’ll learn how to set up the hardware, configure parameters, and program the PLC to achieve reliable servo operation.
Understanding the 111 Telegram in PROFIdrive
PROFIdrive is the standardized communication profile for drive technology over PROFIBUS and PROFINET. The 111 telegram is specifically designed for speed control applications. It defines a fixed structure of process data exchanged cyclically between the PLC and the drive. The telegram consists of a control word (STW1), speed setpoint (NSOLL_A), and status word (ZSW1), speed actual value (NIST_A), among other signals. This standardized approach simplifies integration and ensures interoperability between devices from different manufacturers.
Key signals in Telegram 111:
- STW1 (Control Word 1): Commands like ON/OFF, enable operation, fault acknowledge.
- ZSW1 (Status Word 1): Drive status, faults, and actual state.
- NSOLL_A (Speed Setpoint A): 16-bit speed reference value.
- NIST_A (Speed Actual Value A): 16-bit actual speed feedback.
Hardware Setup: Connecting V90 to Siemens PLC
Before diving into software, ensure the physical connections are correct. The V90 servo drive supports PROFINET communication, which is the preferred network for Siemens PLCs like the S7-1200 or S7-1500. Use standard Ethernet cables to connect the drive’s PN interface to the PLC’s PROFINET port. The drive also requires a 24V DC power supply for control electronics and a main power supply for the motor. Always follow the wiring diagrams in the V90 operating instructions to avoid damage.
| Connection | V90 Terminal | Description |
|---|---|---|
| PROFINET | X150 P1/P2 | Connect to PLC or switch |
| 24V DC Control | X124 L+/M | Power for drive logic |
| Main Power | X1 L1/L2/L3 | 3-phase supply for motor |
| Motor Cable | X2 U/V/W | Connect to servo motor |
Configuring the V90 Drive with 111 Telegram
Using the SINAMICS V-ASSISTANT software or the drive’s BOP (Basic Operator Panel), set the following parameters to enable Telegram 111:
- P0922 = 111 (Selects PROFIdrive telegram 111)
- P0918 = 1 (PROFINET device name, set according to project)
- P0010 = 1 (Quick commissioning mode)
- P0300 = motor type (e.g., 1 for synchronous)
- P0304 = rated motor voltage (from motor nameplate)
- P0305 = rated motor current
- P0310 = rated motor frequency
- P0311 = rated motor speed
After setting these parameters, perform a quick commissioning (P3900 = 1) to calculate motor data. Then, set P0010 = 0 to return to ready state. The drive is now configured to exchange data according to Telegram 111.
PLC Programming: Function Block for Telegram 111
In TIA Portal, you can use the standard motion control blocks or create a custom function block to handle the 111 telegram. The core logic involves mapping the control word and speed setpoint to the drive’s process data output (PDO) and reading the status word and actual speed from the process data input (PDI).
Example control word values (hex):
- 047E: Ready to switch on (no enable)
- 047F: Enable operation (drive runs)
- 04FE: Fault acknowledge (rising edge)
- 047C: Quick stop
A typical function block might have inputs for enable, speed setpoint, and fault reset, and outputs for drive status, actual speed, and fault indication. Inside the block, you construct the control word based on the state machine defined in PROFIdrive. The speed setpoint is scaled: 4000 hex corresponds to 100% of the reference speed (P2000). For example, if P2000 = 3000 rpm, then a setpoint of 2000 hex (8192 decimal) would request 50% speed (1500 rpm).
| Speed Setpoint (hex) | Decimal | % of P2000 | Example RPM (P2000=3000) |
|---|---|---|---|
| 4000 | 16384 | 100% | 3000 |
| 2000 | 8192 | 50% | 1500 |
| C000 | -16384 | -100% | -3000 |
Step-by-Step Implementation in TIA Portal
Here’s a practical guide to set up the communication and program the function block:
- Create a new project in TIA Portal and add your PLC (e.g., S7-1200 1214C) and the V90 drive from the hardware catalog.
- Assign the PROFINET device name to the V90 (must match P0918). Use the “Online & diagnostics” function to assign the name.
- Configure the telegram: In the device configuration of the V90, under “Telegram configuration”, select “Standard telegram 111”. This automatically creates the I/O addresses for the process data.
- Create a function block (FB) in the PLC program. Define the interface with inputs (Enable, SpeedSetpoint, FaultReset) and outputs (DriveReady, ActualSpeed, Fault).
- Write the logic to build the control word based on the state machine. Use the I/O addresses from the telegram configuration to transfer data.
- Call the FB in the main OB1, providing the required inputs and mapping the outputs to global tags.
Troubleshooting Common Issues
Even with careful setup, issues can arise. Here are some common problems and solutions:
| Symptom | Possible Cause | Solution |
|---|---|---|
| Drive not responding | PROFINET name mismatch or cable issue | Check device name and physical connection |
| Fault F7900 or similar | Motor data incorrect or encoder fault | Verify motor parameters and encoder wiring |
| Speed setpoint not working | Control word not enabling operation | Ensure STW1 transitions from 047E to 047F |
| Actual speed reads zero | Encoder feedback not configured | Check P0400 and encoder type |
Advanced Tips for Reliable Operation
For production environments, consider these best practices:
- Use a dedicated PROFINET network for motion control to minimize latency.
- Implement a heartbeat or watchdog timer in the PLC to detect communication loss.
- Scale speed setpoints in engineering units (e.g., RPM) within the function block for easier maintenance.
- Add diagnostic messages to the HMI for quick fault identification.
- Regularly update the drive firmware and TIA Portal to the latest versions for improved performance and security.
Conclusion: The Siemens V90 servo drive with Telegram 111 provides a straightforward yet powerful method for speed control in automation systems. By understanding the PROFIdrive profile, correctly configuring the drive, and implementing a robust function block in the PLC, engineers can achieve precise and reliable motion control. This approach reduces engineering time and ensures compatibility across the Siemens ecosystem.
