RMS R325I User manual

R325I Single Axis Controller/Driver
User Manual
And Commands Guide
Version 1.20
RMS Technologies
2533 N. Carson St. #4698, Carson City, NV 89706-0147
1-877-301-3609
www.rmsmotion.com [email protected]

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R325I Single Axis Controller/Driver Manual 02/13/2006
Thank you for purchasing the R325I Single-Axis Controller/Driver. This product is
warranted to be free of manufacturing defects for one (1) year from the date of
purchase.
PLEASE READ BEFORE USING
Before you start, you must have a suitable step motor, a DC power supply suitable
for the motor and a current resistor. The power supply voltage must be between 4
times and 20 times the motor's rated voltage.
DISCLAIMER
The information provided in this document is believed to be reliable. However, no
responsibility is assumed for any possible inaccuracies or omissions. Specifications
are subject to change without notice.
RMS Technologies reserves the right to make changes without further notice to any
products herein to improve reliability, function, or design. RMS Technologies does
not assume any liability arising out of the application or use of any product or circuit
described herein; neither does it convey any license under its patent rights, nor the
rights of others
Note: This equipment has been tested and found to comply with the limits for a
Class (A) digital device, pursuant to part 15 of the FCC Rules. These Limits are
designed to provide reasonable protection against harmful interferences when the
equipment is operated in its installation. This equipment generates, uses and can
radiated radio frequency energy and, if not installed and used in accordance with the
instruction manual, may cause harmful interference to radio communications. If this
equipment does cause harmful interference the user will be required to correct the
interference.
This Class (A) digital apparatus complies with Canadian ICES-003
Cet appareil numérique de la classe (A) est conforme à la norme NMB-003 du Canada
Special Symbols
Indicates a WARNING and that this information could prevent
injury, loss of property, or even death (in extreme cases).

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R325I User Manual
Product: R325I
Version: 1.20
Date: 02/13/2006
Version History
Version Date Description of Changes
1.20 02/13/2006 New Formatting

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Table of Contents
1. FEATURES......................................................................................5
Pole Damping Technology™............................................................................... 5
Optically Isolated Inputs and Output................................................................. 5
2. ELECTRICAL SPECIFICATIONS.......................................................6
3. OPERATING SPECIFICATIONS .......................................................6
4. COMMUNICATION SPECIFICATIONS..............................................6
5. MECHANICAL SPECIFICATIONS.....................................................7
Dimensions ..................................................................................................................7
6. PIN ASSIGNMENTS........................................................................8
7. CONNECTION SPECIFICATIONS.....................................................9
Connecting the Power ..................................................................................... 10
HyperTerminal Configuration .......................................................................... 10
Setting the Current ......................................................................................... 11
Setting Step Resolution................................................................................... 11
Saving the Configuration................................................................................. 11
Connecting the Motor...................................................................................... 11
Configure the R325I using the DIP Switch....................................................... 12
DIP Switch Run Current Settings................................................................................ 12
DIP Switch Hold Current Settings............................................................................... 12
DIP Switch Step Resolution Settings .......................................................................... 12
8. BASIC STEP AND DIRECTION OPERATION...................................13
9. COMMAND TABLES.......................................................................14
Basic Configuration Commands ....................................................................... 14
Axis Configuration Commands......................................................................... 14
General Operation Commands......................................................................... 14
10. COMMANDS ...............................................................................15
Protocol Syntax............................................................................................... 15
HOMING & POSITIONING................................................................................ 16
VELOCITY & ACCELERATION............................................................................ 16
SETTING CURRENT.......................................................................................... 18
STORAGE & RECALL......................................................................................... 18
MICROSTEPPING............................................................................................. 19
QUERY COMMANDS ......................................................................................... 19
11. RS485 Communication ..............................................................20
12. Troubleshooting ........................................................................22
13. Appendix A ................................................................................23

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1. FEATURES
•Single Axis Driver for Bipolar step motors
•Operates from +15 to 48 VDC
•Phase currents from 0.3 to 3.0 Amp Peak
NOTE: Phase current of 2.7 Amp and above REQUIRES an additional heatsink,
make sure the temperature of the bracket does not exceed 45° C.
•Hold current reduction capability with adjustable current and timeout settings
•Selectable Step Resolution from Full Step to 256x Microstepping
•Has three optically isolated control inputs and one optically isolated control
output
• Software configurable by the temporary use of a plug-in USB module and text
commands from HyperTerminal or any similar terminal emulation software.
• Configuration Parameters stored in non-volatile memory.
• Multiple module control through software assigned single character addresses
• Built-in control routines for trapezoidal position and velocity moves
• Absolute position can be tracked and reported in step resolution increments
• Pole Damping Technology™ implemented within driver board
Dip switches and a RS485 interface are built-in to the R325 Controller. A USB
connection can be used by using the USB485 Converter Card (sold separately).
Pole Damping Technology™
Pole Damping Technology™ (PDT) enhances step motor performance by dampening
each full step in order to create a more accurate and smooth motion profile.
Microstepping the step motor will optimize Pole Damping Technology™. PDT outputs
the correct amount of run and hold currents to the motor, at the right time. Thus, it
will overcome the step motor’s natural tendency to want to forcefully pull towards
the full step ON position.
Optically Isolated Inputs and Output
The default usage of the three optically isolated inputs is Step, Direction and Disable.
The assignment of Disable is fixed; however the other two inputs can be assigned to
other functions as part of software customization. For example one can be used for
Go-Resume and the other for Stop-Quit.
The normal usage of the single optically isolated output is to indicate motion by
sending a pulse every time a step is made.

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2. ELECTRICAL SPECIFICATIONS
Supply Voltage: +15 to 48 VDC
Phase Current: 0.3 to 3.0 Amps Peak
NOTE: Phase current of 2.7 Amp and above REQUIRES an additional heatsink,
make sure the temperature of the bracket does not exceed 45° C.
I/O Specifications
3x Optically Isolated Inputs (1 fixed)
1x Optically Isolated Output
Minimum Motor Impedance: 1.5 mH
Note: The drive may behave unpredictably if the motor you are using has an inductance less
than 1.5 mH.
3. OPERATING SPECIFICATIONS
Maximum Step Frequency: 2.5 MHz
Operating Temperature: Low end – 0°C
High end – Dependent on case temperature,
bracket temperature must not exceed 45° C
Automatic Motor Holding Current reduction available from 0.3 to 2.5 Amps
Logic Timing
Minimum Step Pulse Width 200 nanoseconds
Minimum Step Low Time 200 nanoseconds
Maximum Power-Down Recovery Time 20 milliseconds
4. COMMUNICATION SPECIFICATIONS
Address bytes in the RS485 commands allow multiple units (32 units max) to be
controlled from a single host port.
Interface Type RS485
Baud Rate 57600 bits per second (bps)
# Bits per character 8 data bits
Parity None
Stop Bit 2
Flow Control None

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5. MECHANICAL SPECIFICATIONS
Size: 3.00” x 2.94” x 1.42”
Weight: 4.8 oz
Mounting: Four #6-32 screws, 2.42” x 2.45”
Plate: Aluminum, Hard Anodized
Dimensions

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6. PIN ASSIGNMENTS
A 12-pin pluggable terminal strip connector P1 provides power and the step and
direction control functions for the module. All of these signals are optically isolated.
Open-collector drives are required to provide pulses for Step, levels for Direction,
and Disable. The common +ve supply can be +ve 5 to 30 VDC with respect to the
signal input; however if the supply is greater than 5 VDC then a resistor must be
inserted in series with each signal line to limit the current to 10 mA.
P1 Configuration
Pin No Function
1 Common +ve External
2 Step (in)
3 Direction (in)
4 +5 VDC Internal
5 Disable (in)
6 Motor A+ (out)
7 Motor A- (out)
8 Motor B+ (out)
9 Motor B- (out)
10 Fault (out)
11 Power Ground
12 Power Positive
P1 Connector – Pin 1 Location
CAUTION:Connecting Motor phases (A, A Bar, B, B Bar) to the incorrect location
while the R325 is powered will cause the board to burn. Be sure to insert motor
phases into Pins 6 through 9, in the order of A, A Bar, B, and B Bar. It is
recommended that power is connected last, so that all connections can be
checked before power up.
A separate three pin connector P3 is provided for the RS485 bus interface
P3 Configuration
Pin No Function
1 A Input (+ve)
2 Ground
3 B Input (-ve)
Mating Connectors
P1 Phoenix Contact 1803675
P2 Amp 640441-5
P3 Amp 640441-3
JP1 – Jumper on Pins 7 & 8 (Default)

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7. CONNECTION SPECIFICATIONS
To begin using the R325I, first determine how you will operate the unit: Simple
Controller/Driver or Driver Only. When using the Controller/Driver, insure that
the jumper is located on Pin 7 & 8 on JP1 and that switches 8, 9, and 10 are
in the OFF position, setup must be made with an RS485 connection and
communication can take place using Windows HyperTerminal. When using the Driver
Only portion of the R325I, first remove the jumper located on JP1, use the dip
switches for step resolution and current settings.
Using the R325I as a Driver Unit Only
If using the R325I as a Driver only, be sure to connect the power supply last.
Pin 1: Connect Pin 1 to Pin 4 to use the internal +5 VDC. By using the internal +5
VDC the I/O’s will no longer be optically isolated. If optical isolation is still desired,
use a separate +5 VDC supply and connect the POSITIVE end of the supply to Pin 1.
The NEGATIVE end will connect with the NEGATIVE end of your pulse generator.
Pin 2: Use a pulse generator or function generator to receive pulses into the R325I.
Connect the POSTIVE end of the pulse generator to Pin 2. The NEGATIVE end will be
connected to the NEGATIVE end of the +5 VDC supply if using a separate power
source. If using the internal +5 VDC supply, connect the NEGATIVE end of the pulse
generator to Power GROUND.
Pin 3: To switch the direction of motor rotation, connect Pin 3 with Pin 11, Power
Ground. An open or closed connection to Power Ground will change the direction.
Pin 4: This is the internal +5 VDC. Use this for testing purposes or if optical
isolation of the I/O’s is not desired.
Pin 5: To enable the drive leave this Pin open, disable the drive connect Pin 5 with
Pin 11 (Power Ground). An open or closed connection to Power Ground will enable
and disable the drive, respectively.
Pin 6: Phase A Motor Connection
Pin 7: Phase A Motor Connection
Pin 8: Phase B Motor Connection
Pin 9: Phase B Motor Connection
CAUTION:Connecting Motor phases (A,
A Bar, B, B Bar) to the
incorrect location while the
R325I is powered will cause
the board to burn. Be sure to
insert motor phases into Pins 6 through 9,
in the order of A, A Bar, B, and B Bar. It
is recommended that power is connected
last, so that all connections can be
checked before power up.
Pin 10: The Fault Output is not used in driver only mode. Sits high.
Pin 11: Connect the NEGATIVE of the Power Supply to this terminal.
Pin 12: Connect the POSITIVE of the Power Supply to this terminal. (+15 to 48VDC)

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Connecting the Power
The R325I requires a supply voltage between 15-48 VDC. First, connect the positive
end of the power supply to positive terminal (Pin 12), and then connect the negative
of the power supply to the Ground (Pin 11) on the R325I.
WARNING! Be careful not to reverse the polarity from the power supply
to the driver. Reversing the connection will destroy your driver and void
the warranty.
HyperTerminal Configuration
Configure HyperTerminal needs to properly communicate with the R325I.
Please follow these steps to properly set up HyperTerminal:
1. Open a terminal from your PC by following these steps: Start Menu Æ
Programs ÆAccessories ÆCommunications ÆHyperTerminal
2. Assign a name for your New Connection, “Click Ok”
3. Under “Connect using”, select the COM connection that corresponds to your
PC serial port (i.e. COM 1, COM 2, etc.) then click “OK”
4. Set your Port Settings to:
Bits per second: 57600
Data bits: 8
Parity: None
Stop bits: 2
Flow control: None
Click “OK”
5. Turn on local echo by going to: File ÆProperties ÆSettings tab ÆASCII
Setup: Check the boxes for “Send line ends with line feeds” and “Echo Typed
Characters Locally.” These options will be useful when typing commands in
HyperTerminal. Click ‘OK”, Click “OK”
6. HyperTerminal is ready to send commands
The line turnaround from transmit to receive must be less than one character
interval (191 µS).
The command syntax is as follows:
#<Board Address><Command><Value><cr><lf>
The reply syntax is:
*<Board Address><Command> <Value><cr><lf>
Note: Not all commands will return a value.
Example
Setting the Run Current (RI) to 1500mA (1.5A)
#ARI1500 //Sent Command
*ARI1500 //Received Reply

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Setting the Current
There are two current settings on the R325I.
1. Run Current (RI) – The peak current that the motor will be run at while in
motion.
NOTE: Current of 2.7 Amp and above REQUIRES an additional heatsink, make sure the
temperature of the bracket does not exceed 45° C.
2. Hold Current (HI) – The current that the motor will receive when idle.
*The default board address of ‘A’ is used in all examples, please see “MA” command for more
detail on addresses.
Examples:
To set Run Current to 2000mA (2.0A): #ARI2000
To set Hold Current to 300mA (0.3A): #AHI300
Setting Step Resolution
The R325I is capable of full stepping or 2, 4, 8, 16, 32, 64, 128, and 256
microstepping.
Example: To set Step Resolution to 4x microstepping: #ASR4
Saving the Configuration
In order to have these settings retained upon a power cycle, the data must be saved.
The command to store these settings is “SD” (Save Data).
Example:
To save settings: #ASD
Connecting the Motor
WARNING! Make sure the power is OFF when connecting or
disconnecting motors from the R325I. Damage will occur if the
power is being supplied.
Please refer to your motor documentation for wiring color code.
Connect the corresponding Phase from the motor to the proper pin on the R325.
Motor Phase P1 Connector
Phase A Pin 6
Phase A- Pin 7
Phase B Pin 8
Phase B- Pin 9
Using the R325I
If using the R325I in Step/Direction mode, remove the jumper from Pins 7 & 8 on
JP1, and proceed to Section 8 – Basic Step and Direction Operation.
If using the R325I as a simple controller, please insure that there is a jumper on Pins
7 & 8 on JP1, and refer to the Command Tables in Section 9 and more detailed
descriptions of the Commands in Section 10.

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Configure the R325I using the DIP Switch
R325I DIP Switch Settings
In addition to the Jumper on Pin 7 & 8 on JP1, the Switches 8, 9, and 10 must be “OFF” in
control mode. If using Step & Direction mode remove the jumper.
Run Current
Function SW1 SW2 SW3 SW4
0.3A ON ON ON ON
0.4A OFF ON ON ON
0.5A ON OFF ON ON
0.6A OFF OFF ON ON
0.8A ON ON OFF ON
1.0A OFF ON OFF ON
1.2A ON OFF OFF ON
1.4A OFF OFF OFF ON
1.6A ON ON ON OFF
1.8A OFF ON ON OFF
2.0A ON OFF ON OFF
2.2A OFF OFF ON OFF
2.4A ON ON OFF OFF
2.6A OFF ON OFF OFF
2.8A ON OFF OFF OFF
3.0A OFF OFF OFF OFF
WARNING: Current of 2.7 Amp and above REQUIRES an additional heatsink, make sure
the temperature of the bracket does not exceed 45° C
Hold Current (Percent of Run Current)
Function SW5 SW6
0% ON ON
33% OFF ON
66% ON OFF
100% OFF OFF
Step Resolution
Function SW7 SW8 SW9 SW10
Full Step* OFF OFF OFF OFF
2X ON OFF OFF OFF
4X ON ON OFF OFF
8X ON OFF ON OFF
16X ON ON ON OFF
32X ON OFF OFF ON
64X ON ON OFF ON
128X ON OFF ON ON
256X ON ON ON ON
*The power must be turned OFF when switching in and out of Full Step mode.
Notes:
1. Switches 8, 9 , and 10 must be set to ‘OFF’ to use the R325I in control mode. This is
in addition to installing the jumper on JP1 Pins 7 and 8.
2. Installing a jumper on JP1 Pins 9 and 10 runs the factory test routine

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8. BASIC STEP AND DIRECTION OPERATION
The four control signals Step, Direction, Disable, and Fault Out are optically isolated,
with a common positive connection (usually 5 VDC).
The common positive connection (Pin 1) is typically 5 VDC. Each of the inputs is set
to TRUE by supplying a signal level 5V below the common positive connection
powering the optical isolators. The input is set FALSE by putting the signal within 0.5
VDC below the common positive value.
Example: If 5 VDC is supplied to Pin 1 (common positive connection), TRUE is 0V,
and FALSE is any value between 4.5 VDC to 5 VDC.
For test purposes, and some applications where input isolation is not required, the
internal 5 VDC supply at Pin 4 of the I/O connector can be used as the common
positive connection, by linking pins 1 and 4 on the connector.
If this is done then each input is set TRUE by bringing the voltage level at the input
equal to, or more negative than the Power Supply negative connection at Pin 11.
With this arrangement Direction, Disable, and Fault Out control can be effected by
simple switch closure between the input and the power negative connection at Pin
11.
If the Step input is obtained from a Function Generator, then careful adjustment of
the Offset control is needed to ensure that the negative level of the input signal is
equal to, or more negative than, the power negative connection at Pin 11.
The minimum duration of the active (negative) Step input signal level is 400
nanoseconds and also this is the minimum for the inactive (positive) level. This limits
the maximum usable step rate to 2.5 MHz.
The optimum operating arrangement (minimum power usage) is for a constant width
negative going pulse of 400 nanoseconds with the pulse interval varying with pulse
rate.
For test purposes, setting the Function Generator duty cycle to 50%, and just
varying frequency is satisfactory.

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9. COMMAND TABLES
To begin using the R325I in command mode, insure that the jumper is located
on Pin 7 & 8 of JP1 and that switches 8, 9, and 10 are in the OFF position,
setup must be made with an RS485 connection and communication can take place
using Windows HyperTerminal. When using the Driver Only portion of the R325I, first
remove the jumper located on JP1, use the dip switches for step resolution and
current settings.
Basic Configuration Commands
Function Query/New Code Value Minimum Maximum Default
Load Defaults N LD None - - -
Save Data N SD None - - -
Module Address Q/N MA Numeric 65 (A) 90 (Z) 65 (A)
Axis Configuration Commands
Function Query/New Code Value Minimum Maximum Default
Acceleration Q/N AC Numeric 1 100 10
Hold Current Q/N HI Numeric 0 3000 300
Hold Timeout Q/N HT Numeric 100 5000 5000
Min. Velocity Q/N MV Numeric 256 15,000 256
Percent Fast
Decay
Q/N PF Numeric 0 3 2
Run Current Q/N RI Binary 300 3000 1000
Read Switches Q RS Numeric 0 15 -
Step Resolution Q/N SR Numeric 1 256 16
Start Velocity Q/N SV Numeric 256 15,000 1,000
Velocity Limit Q/N VL Numeric 256 15,000 15,000
Zero Position N ZP None - - -
General Operation Commands
Function Query/New Code Value Minimum Maximum Default
Absolute Position N AP Numeric -2147483646 2147483647 -
Current Position Q/N CP Numeric -2147483646 2147483647 -
Current Velocity Q CV Numeric 0 50,000 -
Firmware Rev. Q FR Numeric - - -
Home Axis N HA Numeric 0 1 -
Move Status Q MS Numeric 0 2 -
Position Move N PM Numeric -2000000000 2000000000 -
Step Back N SB None - - -
Step Forward N SF None - - -
Stop Motion N SM None - - -
Velocity Move * Q VM Numeric -50,000 50,000 -
* Velocity Moves in the range –249 to 249 are not legal except zero

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10. COMMANDS
Protocol Syntax
Command Format: #<Address><Command><value><CR><LF>
Example: #ACP1000<CR><LF>
Sets Driver A to the current position of 1000
To query a command use the following format
Query Format: #<Address><Command><CR><LF>
Example: #AAC<CR><LF>
Queries Driver A for the current Acceleration Value
The response would be in the following format
Response Format: *<Address><value>
Example: *AAC10
The Acceleration Value for Driver A is 10
<CR><LF> stand for "Carriage Return" and "Line Feed" respectively. These are NOT
characters to be typed in. For direct keyboard users, these values are executed when
the "Return" key is pressed. For programmers, a "Carriage Return" and "Line Feed"
(also known as a "New Line") command needs to be executed after each command.

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Command
(Case Sensitive) Operand Example Description
HOMING & POSITIONING
HA 0 = Forward
1 = Reverse #AHA1
Motor turns in
the reverse
direction
Home Axis - Command Only
- Causes the motor to move at the preset Start Velocity (SV) in
the direction set by the command value. Motion stops when the
index input of a device on the input pin goes TRUE then stops
and sets absolute position to zero. Motion can also stop by the
entry of a Stop Motion (SM) command.
- Forward is defined as the direction the motor turns when the
‘Direction’ input (P1-3) is set TRUE, or there is no connection to
this input.
P2 Configuration
Pin No Function
1 GND
2 Index
3 -
4 +5 V
5 -
CP +/–
2,147,483,646 #ACP1000 Sets the current
position to be
1000
#ACP
Returns the
current position
of the motor
Current Position - Command or Query.
- Returns the absolute position of the axis if no value is passed.
Valid after power cycles if a Save Data Command is issued before
power down. Can be used to set current position value.
The units are steps at the current step resolution (value becomes
invalid with step resolution changes). The absolute position scale
is set to zero by the Zero Position command (ZP) or the
execution of a Home Axis (HA) command.
ZP - #AZP
Sets absolute
position to zero
Zero Position - Command Only
- Sets the current value of the Absolute Position scale to zero
Note: This command functions differently between R325I and
R325IE
VELOCITY & ACCELERATION
AC 1 - 250
#AAC1
Sets
Acceleration to
1000 PPS^2
Acceleration - Command or Query
Default = 10
Used to shape the acceleration and deceleration ramps of
position moves, and the rate of velocity change for velocity
moves.
Does not affect any of the basic step and direction move
operations
Acceleration Factor * 1000 Pulses per Second
AP +/–
2,147,483,646 #AAP1000
Moves to
absolute
position of 1000
Absolute Position - Command Only
- Used to make an absolute position move (in step resolution
units).
CV +/- 50,000
#ACV Current Velocity - Query Only - Only valid when a Position Move (PM) or Velocity Move (VM) is
in progress. Otherwise returns zero.
MS 0 -2 #AMS Move Status - Query Only
- Reads Motion Status. Returns 0 for No Motion, 1 for Position
Move, and 2 for Velocity Move.
MV 256 - 50,000 #AMV500
Sets minimum
velocity to 500
SPS
Minimum Velocity - Command or Query
Default = 256
- Reads or sets the minimum velocity for both Position and
Velocity command moves. The units are steps (at the current
Step Resolution) per second.

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Command
(Case Sensitive) Operand Example Description
VELOCITY & ACCELERATION (cont.)
PM +/-
2,000,000,000 #APM1000
Makes a 1000
step move from
the current
position
Position Move - Command Only
- Causes a ‘Relative Motion’ Position Move, using an
approximately trapezoidal profile. The initial velocity is defined
by ‘Start Velocity’ (SV), the profile ramp is defined by
‘Acceleration’ (AC), and the ‘Constant Velocity’ step rate by
‘Velocity Limit’ (VL). ‘Minimum Velocity’ (MV) is used to ensure
that the deceleration ramp does not set velocity to zero before
the target position is reached.
- It should be remembered that, while the ‘Position Move’ value
defines the number of steps to be made from the current
position, the value returned by ‘Current Position’ (CP) both
before and after a ‘Position Move’ are on an ‘Absolute’ step count
scale.
- CP readings can be used to determine PM values required to
reach any given position on the ‘Absolute’ step count scale.
Note: This command does not return a value.
SB - #ASB
Moves one step
back
Step Back - Command Only
- Makes a single step move at the current step resolution
- Forward is defined as the direction the motor moves with the
‘Direction’ input in the FALSE state or with no connection.
Backwards is thus the direction the motor moves when the
‘Direction’ input is in the energized or TRUE state.
SF - #ASF
Moves one step
forward
Step Forward -Command Only
- Makes a single step move at the current step resolution
- Forward is defined as the direction the motor moves with the
‘Direction’ input in the FALSE state, or with no connection.
Backwards is thus the direction the motor moves when the
‘Direction’ input is in the energized or TRUE state.
SM - #ASM
Stops any
Position or
Velocity move in
progress
Stop Motion Command Only
- This command can be used to affect an end to any Position
Move or Velocity Move in progress. It has no effect on motion
produced by the Step and Direction inputs.
SV 256 - 15000 #ASV500
Start velocity
set to 500 PPS
Start Velocity - Command or Query
Default = 1000
- Reads or sets the velocity used for the first step in a position
move in steps/sec. Value based on motor performance.
VL 256 - 15000 #AVL5000
Sets the velocity
limit to 5000
steps/sec
Velocity Limit - Command or Query
Default = 15000
- Reads or sets the velocity used for Velocity Moves and the
constant velocity portion of a Position Move.
VM 250 - 50,000,
-250 - -50,000
or 0
#AVM1000
Starts a velocity
move of 1000
steps per
second
Velocity Move - Command Only
- The sign of the value determines the direction (positive for
forward and negative for backward) in which the velocity move is
made. The value sets the step rate in steps per second at the
current step resolution. Velocity cannot exceed Velocity Limit.
- The move begins at the set ‘Minimum Velocity’ (MV) with the
speed ramping to the command velocity at the rate set by
‘Acceleration’ (AC).
- Changes to new velocity values from new VM commands, will
also occur at the rate set by ‘Acceleration’ (AC).
Note: No value is returned. Zero velocity makes an abrupt stop

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Command
(Case Sensitive) Operand Example Description
SETTING CURRENT
HI 0-3000 #AHI300
Sets the Hold
Current to
300mA (0.3A)
Hold Current - Command or Query - 0 to 3000
Default = 300
- Reads or sets the motor Holding Current in 100 milliamps
increments. The value does not round.
RI 300 - 3000 #ARI1000
Sets the run
current to 1000
mA (1.0 Amp)
Run Current - Command or Query
Default = 1000
- Sets the motor Phase Current for any form of motion in
milliamps.
300 = 300mA (0.3 Amp)
2500 = 2500mA (2.5 Amp)
The last two numbers of the value are not read.
350 = 300mA, 2499 = 2400mA
- The set ‘Run Current’ is maintained for a time set by ‘Hold
Timeout’ (HT) before dropping to the current set by ‘Hold
Current’ (HI)
NOTE: Current of 2.7 Amp and above REQUIRES an
additional heatsink, make sure the temperature of the
bracket does not exceed 45° C
HT 100 -5000 #AHT100
Sets the Hold
Timeout to 100
mS
Hold Timeout - Command or Query
Default = 5000
- Reads or sets the time interval in milliseconds after any motor
movement, before the motor current is changed from Run
Current to Hold Current.
STORAGE & RECALL
LD - #ALD
Loads all the
default values
Load Defaults - Command Only
- Loads all of the unit Default parameter values. A Save Data
(SD) command must be issued to have these values retained
during a power cycle.
Default values are:
Module Address 65 (A)
Acceleration 50
Absolute Position 0
Percent Fast Decay 2
Hold Current 300 (0.3A)
Hold Timeout 5000
Minimum Velocity 256
Run Current 1000 (1.0A)
Step Resolution 16
Start Velocity 1000
Velocity Limit 15000
SD - #ASD
Saves data
Save Data - Command Only
- This command causes a set of parameter values to be written
to non-volatile memory. On power up the last set of values
written are set to be the parameter initial values.
-The parameters whose values are thus saved are:
My Address
Absolute Position
Velocity Limit
Minimum Velocity
Start Velocity
Acceleration
Hold Timeout
Step Resolution
Run Current
Hold Current
Percent Fast Decay

RMS Technologies Page 19 Version 1.20
R325I Single Axis Controller/Driver Manual 02/13/2006
Command
(Case Sensitive) Operand Example Description
MISC
PF 0 - 3 #ACD1
Sets Mixed
Mode damping
to 15%
Percent Fast Decay - Command or Query
Default = 2
- Allows the Damping Mode of the driver IC to be set.
0 = Fast Decay
1 = Mixed Mode 15%
2 = Mixed Mode 48%
3 = 100%
The optimum setting will vary with motor inductance and step
rate; however the default ‘Mixed Mode’ setting will work well with
almost all motors.
MICROSTEPPING
SR 1, 2, 4, 8, 16,
32, 64, 128,
256
#ASR4
Sets the step
resolution to 4x
Step Resolution - Command or Query
Default = 16
- Reads or sets the current step resolution
Allowed values are:
256 for 256x
128 for 128x
64 for 64x
32 for 32x
16 for 16x
8 for 8x
4 for 4x
2 for 2x
1 for 1x
QUERY COMMANDS
FR - #AFR Firmware Revision - Query Only
- Returns 3 digit part code followed by 3 digit firmware revision
value.
Reply
*AFR325100 //R325 firmware revision 1.00
MA 65 - 90
#AMA88
Sets the unit
address to 88
(‘X’)
My Address - Command or Query
Default = 65
- Reads or sets the unit address. The value read or entered is the
decimal value of the ASCII character designated as the unit
address. (65 = ‘A’ and 90 = ‘Z’)
The change to a new address is immediate, in that the command
response will use the new address
RS - #ARS
Reads the
switch inputs
Read Switches - Query Only
- Reads the TRUE (1) or FALSE (0) state of the three optically
coupled inputs, combined into a single three-bit value. This
command is used to check the correct operation of this interface.
- The value order of the inputs is ‘Direction’, ‘Disable’, and ‘Step’;
in descending order.
‘Direction’ has the value 4 (100)
‘Disable’ has the value 2 (010)
‘Step’ has the value 1 (001)
TI - #ATI
Reads the
switch inputs
Test Inputs - Query only
Step, Direction, and Disable all return a value in decimal form.
The value order of the inputs is:
‘Direction’, ‘Disable’, and ‘Step’; in descending order.
‘Direction’ has the value 4 (100)
‘Disable’ has the value 2 (010)
‘Step’ has the value 1 (001)
Reply
*ATI3 // 3 = ‘011’

RMS Technologies Page 20 Version 1.20
R325I Single Axis Controller/Driver Manual 02/13/2006
11. RS485 Communication
1. The Interface
The EIA specification RS485 defines an integrated circuit that is to be used to connect up to
32 nodes to a two-wire party line bus that does not exceed 4,000 ft. in length, and for use
with data rates up to 10M Baud.
The two-wire bus must be terminated at one-end for short wire runs and at both ends if the
runs exceed 20 ft. One of the two wires must be biased positive with respect to the other by
approximately 700 millivolts.
A single 5VDC supply can be used to power the interface IC, and this same supply can be
used to satisfy the bias and termination requirements. A 681 ohm 1% resistor is connected
between the +5VDC supply and the positive line. A second 681 ohm 1% resistor is connected
between ground and the negative line, and a 220 ohm 1% resistor is connected across the
two lines. The transceiver A terminal is connected to the negative line and the B terminals to
the positive line.
For wire runs over 20 ft, twisted pair cable with a characteristic impedance of approximately
100 to 200 ohms, and the far end of the run should be terminated by a 150 ohm resistor
across the line pair. For runs under 20ft almost any wire can be used.
2. The Protocol
One node on the bus is designated ‘Master’ and all other nodes on the bus ‘Slaves’. The
Master only initiates communication, and does so by sending a message that includes the
address of a specific Slave. All Slaves read the message, but only the addressed Slave
replies.
The outgoing message from the Master is ‘framed’ by always starting the message with the
‘#’ character (0x23) and ending with the linefeed character (0x0A). The reply from the Slave
is framed by always starting with the ‘*’ character (0x2A) and ending with the linefeed
character (0x0A).
The Slave address is the first character after the ‘#’ in the outgoing message, and the first
character after the ‘*’ in the reply. For ease of use RMS Technologies restricts the range of
address characters to the range of capital letters ‘A’ to ‘Z’, with ‘A’ being the default.
Again for ease of use RMS Technologies restricts the other characters in the message to
ASCII printable characters. This enables the default Windows terminal emulation program
HyperTerminal to be used for configuring and testing modules. However this restriction and
the restricted address range are not an official part of the protocol. Any of the 8 bit character
values other than the framing characters can be used for the address and as any other part
of the message.
3. Messages
Messages should be transmitted as a continuous character stream with less than a half
character time between characters.
Messages are classified as either ‘Commands’ or ‘Queries’. Commands instruct the
designated Slave to do something. Queries request the designated Slave to provide
information.