How do I send a start/stop and a speed command to the Altivar Process Drive over Ethernet (Modbus TCP) protocol?

Resolution:

To send Start/Stop commands and a speed reference to an Altivar Process Drive over Ethernet using Modbus TCP, configure the drive according to the desired control profile.

Unit ID 1

When not using the I/O Scanner, set the Modbus Unit ID to 1.

On the drive:

[Communication] → [Comm Parameters] → [Modbus SL] → [Modbus Fieldbus]

• Set Modbus Address = 1

CiA402 / DRIVECOM Profile

Go to:

[Complete Settings] → [Command and Reference] → [Control Mode] (CHCF)

Set CHCF to:

• [Not Separ.], or
• [Separate Mode]

The drive will follow the CiA402 profile, referred to as DRIVECOM on older products.

Command Word Register: 8501

To start the drive, write the following decimal values to register 8501 in sequence:

6 → 7 → 15

After initialization:

• 7 = Stop
• 15 = Run

I/O Profile

If CHCF is configured for I/O Profile, use the following settings:

[Communication] → [Comm Parameters] → [Modbus SL] → [Modbus Fieldbus]

• Set Modbus Address = 1

[Complete Settings] → [Command and Reference] → [Control Mode] (CHCF)

• Set to [I/O Profile]

Registers:

• 8501: Command Word, 16-bit
• 8502: Frequency Reference, 0.1 Hz units
• 8602: Speed Reference, 1 rpm units

To start or stop the drive under I/O Profile, toggle Bit 0 of command word 8501.

Once the run command has been sent, provide the speed reference by writing to:

• 8502 for frequency in 0.1 Hz increments, or
• 8602 for speed in 1 rpm increments.

When using register 8602, make sure [Nominal Motor Speed] is correctly configured in the [Motor Parameters] menu.

Unit ID 255 - I/O Scanner

When using the I/O Scanner, use Unit ID 255.

• The Modbus Address can remain at 0.
• Enable the I/O Scanner through SoMove.
• The drive will then use the configured I/O Scanner input/output tables.

For additional configuration details, refer to the FAQ “How do I enable and configure the I/O Scanner on the Altivar Process Drive?”.