FB#.SSIBAUD

Description

FB#.SSIBAUD sets the baud rate at which to run the SSI encoder and is only used and updated when FB#.SELECT = 36 (SSI). FB#.SSIBAUD is ignored for other values of FB#.SELECT. It is recommended to leave this value set to its default unless issues arise when connecting to an SSI feedback that cannot be resolved through changing FB#.SSITYPE. It is also recommended to set this parameter before setting FB#.SELECT to 36.

As the number of single-turn and multi-turn bits increases for an SSI encoder, the baud rate may need to be increased in order to transmit all bits of data in the time required by the drive. Due to rounding, the drive will set the actual baud rate used as close to the desired baud rate written to this command. Reading FB#.SSIBAUD after a write will return the actual baud rate that was set by the drive, which may differ from the exact value written.

Example

-->FB3.SELECT 1
-->FB3.SSIBAUD
757575 [Hz]
-->FB3.SSIBAUD 900000
-->FB3.SSIBAUD
900000 [Hz]
-->FB3.SELECT 36 
-->FB3.SSIBAUD
925925 [Hz]

Determining Appropriate BAUD Rate

  1. Confirm the SSI Configuration
    Make sure FB#.SINGLETURNBITS, FB#.SETMULTITURNS, and FB#.SSITYPE are set correctly.

  2. Consider cable length
    Longer cables require lower clock frequencies to avoid signal integrity issues (reflections, capacitance, damping).
    Recommended maximum clock frequency:

    3. Clock Frequency (Buad Rate) Recommended Cable Length Notes/When to Use
    758 (min) - 800 kHz 50+ m Safe baseline for moderate/long cables; low risk of errors; good for 30 - 50 m runs.
    1 MHz 30 - 50 m Common reliable choice; balances low latency (~25–30 µs read for 25-bit frame) and reach.
    2+ MHz <3 - 40 m High-speed option for shorter cables; requires excellent shielding/termination.

  3. Test Incrementally
    Most SSI encoders have an upper baud rate limit of 1 to 2 MHz. Start with a value near the lower limit of the drive around 800 kHz and incrementally increase the value, say 200 kHz at a time, until communication errors or unreliable behavior is noticed such as position jumps, noise, or missing updates.

Versions

Action Version Notes
Implemented 02-12-01-000

General Information

Type

Read/Write

Units

Hertz

Range

757,575 to 25,000,000

Default Value

757,575

Data Type

Integer

Stored in Non-Volatile Memory

Yes

Variants Supported

All variants are supported.

Industrial Ethernet Information

EtherCAT CoE and CANopen

Command

Index

SubIndex

Data Type

Units

Float Scale

Access

PDO Mappable

FB1.SSIBAUD

3500h

20h

Unsigned32

-

-

Read/Write

No

FB2.SSIBAUD

3501h

20h

Unsigned32

-

-

Read/Write

No

FB3.SSIBAUD

3502h

20h

Unsigned32

-

-

Read/Write

No

FB5.SSIBAUD

3504h

20h

Unsigned32

-

-

Read/Write

No
EtherNet/IP

ID

Instance

Attribute

Name

Data Type

Access

User Mappable

30860

1

30860 (0x788c)

FB1.SSIBAUD

Unsigned32

Read/Write

Yes

30861

1

30861 (0x788d)

FB2.SSIBAUD

Unsigned32

Read/Write

Yes

30862

1

30862 (0x788e)

FB3.SSIBAUD

Unsigned32

Read/Write

Yes

30864

1

30864 (0x7890)

FB5.SSIBAUD

Unsigned32

Read/Write

Yes
PROFINET

Parameter

PNU

Data Type

Access

Units

FB1.SSIBAUD

30860

Unsigned32

Read/Write

-

FB2.SSIBAUD

30861

Unsigned32

Read/Write

-

FB3.SSIBAUD

30862

Unsigned32

Read/Write

-

FB5.SSIBAUD

30864

Unsigned32

Read/Write

-