Control Protocols of Motion Control Devices

www.zaber.com • simplifying motion control
Simplifying Control Protocols
Zaber Technologies

Every motion controller has its own
command protocol.
command protocol
(n.) series of rules that dictates the format of
conversation between you and the motion controller.

The command protocol affects:

How intuitive the controller is to use.

How quickly the controller can communicate.

How quickly the controller can communicate.
The type of device(s) that the controller can
communicate with.

Having an open, consistent, easy-to-
use protocol is important because...

It makes it easy to integrate devices quickly into an
application.

It makes it easy to integrate devices quickly into an
application.
It reduces the time it takes for users to become
proficient with the controls.

Zaber’s devices use two command
protocols.

protocols.
ASCII
An easy-to-use and intuitive protocol for
communicating in plain text.

protocols.
ASCII
BINARY
A 6-byte binary protocol designed for relaying
commands in a consistent, compact format.

What’s the difference?

Zaber’s A- and X-Series devices can use both Binary and
ASCII protocols; T-Series can use just Binary.
ASCIIBINARY

Binary communicates in command numbers. ASCII
communicates in plain text.
ASCIIBINARY

Each protocol has its own benefits. Binary is simple,
with concise commands. ASCII is easy to use, and it
is compatible with many devices. It also offers added
support for new features.
ASCIIBINARY

Binary’s simplicity may limit the expandability and
complexity of its command list. While ASCII offers ease
of use, its commands do not have a consistent length.
ASCIIBINARY

More information about
each protocol is available
on Zaber’s Support wiki:
www.zaber.com/support

Now, let’s focus on each protocol and
how you can use them to communicate
with your devices.

First, let’s look at Binary.
BINARY
A 6-byte binary protocol designed for relaying
commands in a consistent, compact format.

BINARY
Every command that is sent and every response that is
received back from the controller contains three pieces
of information.

Device number
executing the command
(1 byte)
BINARY
Multiple devices can be chained in a series. The device
number indicates which device in a daisy-chain should
respond to the command.

Device number
(1 byte)
The number of the
command or setting
(1 byte)
BINARY
The number of the command or setting indicates the
action being executed.
The number of the command or setting indicates the
action being executed.

Device number
(1 byte)
The number of the
command or setting
(1 byte)
A data value
(4 bytes)
BINARY
The meaning of the data value will depend on the
command.

For example:
Let’s say you want to send a command to the first
device in the series (device number 1) to find the home
position (command number 1).
Command 1: 1, 1, 0, 0, 0, 0

For example:
Then, you want to send another command to move
forward relative to the current position (command
number 21) by 1000 microsteps.
Command 1: 1, 1, 0, 0, 0, 0
Command 2: 1, 21, 232, 3, 0, 0

In the first command, the data value is 0 because
the home command does not require any additional
information to run.
Command 1: 1, 1, 0, 0, 0, 0
Command 2: 1, 21, 232, 3, 0, 0

In the second command, the four data bytes are
arranged in order of least significant byte to most
significant byte. Software is usually used to handle the
data conversion.
Command 1: 1, 1, 0, 0, 0, 0
Command 2: 1, 21, 232, 3, 0, 0

Each time a command completes, the controller will
send back a response in the same format.
Command to device 1, 1, 0, 0, 0, 0
...stage retracts to home...
Response from device 1, 1, 0, 0, 0, 0

Now, let’s look at ASCII.
ASCII

Plain text commands
ASCII
The ASCII protocol is available on Zaber’s A-Series
devices with firmware version 6.06, and all X-Series
devices. ASCII allows for plain text communication
between a computer and a controller.

For example:
Let’s say you want to command a device to move to
a position 1000 microsteps forward from the current
position.
Command 1: /move rel 1000 9

For example:
Then, let’s say you want to command the device to find
the reference position.
Command 1: /move rel 1000
Command 2: /home
9
9

The controller will respond, letting you know that
the command has been received and that it will be
executed, or that the command has been rejected and
why.
Command to device /01 home
Response from device @01 1 OK IDLE -- 0
...device begins to move...
9
9

Simple, right?
ASCII

Besides simplicity, there are a number
of benefits to this protocol.

It’s simple to use because it’s text-based and
designed for readability.

It’s easy for new users to be able to pick up
the communication quickly.

It’s easy for new users to be able to pick up
the communication quickly.
Using ASCII characters for control allows
compatibility with a wide variety of devices,
like PLCs (programmable logic controllers).

Faster communication speeds are supported,
which allows for further compatibility.

Faster communication speeds are supported,
which allows for further compatibility.
Added support for new features and
commands, such as multiple limits,
programmable actions, and I/Os.

Now that we know what these
protocols are, how do we use them?

Software, such as our free, open-source
Zaber Console, facilitates the use of
these protocols on our positioners.
ASCII
Binary

Other programs, such as LabVIEW, can
also be used. Zaber offers LabVIEW
drivers for controlling devices with
ASCII or Binary protocol.
ASCII
Binary

Visit www.zaber.com/software or
email contact@zaber.com for more
information.
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Control Protocols of Motion Control Devices

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