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 Notes on Boot-Up sequence of SmartMotors with regards to
communications
Multiple motors on a
communications line
RS-232
RS-485
Pre-Addressed Motors on Boot-Up
Global addressing
Addressed or De-Addressed state
Addressing SmartMotors
from a Host PC or other Serial Device
Notes on Boot-Up sequence of SmartMotors with regard
to communications:
They default to 9600 Baud, no parity 8 data bits and 1 stop bit.
(9600,N,8,1). All SmartMotors boot
up in ECHO_OFF mode with no address.
This means they will respond to globally addressed commands, i.e.
commands proceeded by nothing, or a dec128 (or hex80). Within the first 200msec's or so of
power up, if they have not received any serial communications, they will
begin executing code previously downloaded to them from the top
down. If the Code begins with RUN?
, execution will stop at that line until a RUN" is received via RS-232
serial port.
Multiple motors on a communications line
If multiple motors are to be placed on a communications line, they must
be set up properly to avoid communications errors.
RS-232
If RS-232 is used from a host PC or other RS-232 compatible device, all
motors must be in ECHO mode. While
in ECHO mode, all data reaching a motor's received port will be echoed"
back out it's transmit port. Since
RS-232 serial lines must be daisy-chained together, the motors must be in
ECHO mode to work properly. An
RS-232 chain of motors can be addressed from a host or master without the
motors containing programs.
RS-485
If RS-485 is used, all motors must be in ECHO-OFF mode. RS-485 is a parallel communications
network. If any motor was to echo
out commands received, it would cause all motors or any other devices on
the network to get hit with the same data. An RS-485 chain requires each motor to
have an internal program with a unique address.
Note: SmartMotors use 2 wire RS-485 standards. This means line
biasing determines whether or not the motor is in transmit mode or
receive mode at the hardware level.
To insure motors do not hang up in the transmit mode, there must
be a minimum of a 200mVolt differential between RS-485 A and B
channels. This is easily achieved
by placing a pull down resistor of about 500 Ohms from the B channel to
ground somewhere on the RS-485 network.
All SmartMotors have a 5Kohm pull-up resistor on both A and B
channels already. The 500 Ohm resistor will provide the enough biasing
needed to make the hardware default to the receive state. If there are long distances between
motors, it may be necessary to provide a resistance across channels A and
B. A 200 Ohm resistor wired from A
to B at the remote end of the RS-485 line should provide ample voltage
drop for the needed biasing. If
the above electrical rules are not applied, communications cannot be
guaranteed to work.
Pre-Addressed Motors on Boot-Up
If
it is desired for the motor to have an address on boot-up, the motor must
have a program downloaded to it with the set address command at or near
the top of the program.
Example:
SADDR1 will set the
motor's address to 1.
The motor address command uses integer numbers 1-120, however to
specifically address a particular SmartMotor, you must precede the
desired command with decimal or hex equivalent addresses with an offset
of dec128.
Example: If a motor's program begins with SADDR1, then a command
specifically meant for that motor must be preceded by dec129 or hex81.
Example: To set commanded velocity on motor 1 to 1000 you would
transmit the following: hex81V=1000
To set commanded acceleration on motor 2 to 500 you would transmit the
following:
hex82A=500
The commands must be followed by either a carriage return or space
character (dec13 or dec10).
These same rules apply to one SmartMotor talking to another. Once an address has been transmitted,
it need not be transmitted again with additional commands until it is
time to change the address.
Addressed commands can be sent out by SmartMotors as well as host
computers via use of the PRINT commands in proper format.
Example: PRINT(#131,"A=1200",#13)
The above code sends out dec131 immediately followed by A=1000
immediately followed by a carriage return. PRINT(#131,"A=1200 ) would give the
same result because a space was included after A=1200, and a space counts
as a delimeter.
Global addressing:
As mentioned at the beginning, all motors without an address respond to
any command preceded by dec128 or hex80.
This is also true for any motor with an address that is not in
sleep" mode. If a motor is in
Sleep mode, it will only start listening again if the WAKE command
preceded by its address is sent to that motor.
Example:
If hex85SLEEP is transmitted, motor 5 will
go into sleep mode."
If hex80x=123 is transmitted, every motor
on the serial line will have
variable x updated to 123
except motor 5.
If hex85WAKE is transmitted, motor 5 will
wake up"
and will respond once again to
commands.
Addressed or De-Addressed state:
It is important to understand addressed or de-addressed states of
SmartMotors. These states
determine whether or not a SmartMotor will respond to commands. Lets assume for example that we have 5
motors on a communications network.
All of them have programs downloaded with addresses 1-5
respectively via the SADDR command.
On Boot-up all are ready to listen. They will respond to either a
globally addressed command or a specific motor will respond to a
specifically addressed command.
Once a specific address is sent out on the line, that motor will
remain in the addressed" state.
All other motors will be in the de-addressed" state. What this means is that from that point
on, any command sent out to the motors without an address proceeding it,
will be acted upon only by the motor in the addressed state. All other motors will basically ignore
anything received. By sending out
a command preceded by the global address (hex80 or dec128), all motors
will be placed into the addressed" state and will remain in that state
until another specific address is transmitted. Under this case of 5 motors addressed
1-5 respectively, if a hex89 for example or any other address outside of
hex80-hex85 is sent, all motors would become de-addressed". No motor would respond to any command
until an address within the range of motors on the line is received. This does come in handy if other
Non-SmartMotor devices are on the same network.
For example: suppose you have the same 5 SmartMotors on line with
a barcode reader or temperature controller. If you wanted to send set-up parameters
to these devices but wanted to insure the SmartMotors would ignore the
set-up parameters (since they are more than likely not even valid
SmartMotor syntax), you could de-address" all SmartMotors by sending out
an address outside the bounds of any motor on the line. Most RS-485 devices operate this way.
Addressing SmartMotors from a Host PC or
other Serial Device
Note: This only applies to an RS-232 serial daisy chain. It will not work on an RS-485
network. Motors must be
pre-addressed in downloaded programs for an RS-485 network to work at
all. It is important to realize
the boot-up state of SmartMotors from the first section to understand
this sequence. Please review it if
you have not already done so.
Since SmartMotors without addresses default to address zero (hex80 or
dec128), a sequence of commands must be issued in proper order to achieve
addressing of the SmartMotors.
SmartMotors without programs downloaded into them will not retain
addresses from this procedure upon loss and return of power!
The following is an example sequence of addressing 3 SmartMotors from the
SMI software terminal screen.
Assumptions are as follow:
1. Host PC is set up for 9600 Baud,N,8,1 since this is the power-up
default for SmartMotors.
2. Three SmartMotors are wired in serial daisy chain with Tx of Host PC
wired to Motor-1 Rx, Motor-1 Tx wired to Motor-2 Rx, Motor-2 Tx wired to
Motor-3 Rx, Motor-3 Tx wired to Host PC Rx.
(Tx is RS-232 transmit, Rx is RS-232 Receive)
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0ECHO_OFF
0SADDR1
1ECHO
1SLEEP
0SADDR2
2ECHO
2SLEEP
0SADDR3
3ECHO
3SLEEP
1WAKE
2WAKE
3WAKE
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Places all motors in echo off
Set first motor to address 1
Set it to echo mode so the next motor will be able to receive commands
Set it to sleep mode so it will not act upon following commands
Set next motor to address 2 and repeat sequence
Set all motors to wake status.
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Note: SMI Software
automatically replaces leading numbers in commands with a decimal offset
of 128. In other words, 0ECHO_OFF
resulted in (dec128)ECHO_OFF" being transmitted.
This is the equivalent from any other software source:
(dec128)ECHO_OFF
(dec128)SADDR1
(dec129)ECHO
(dec129)SLEEP
(dec128)SADDR2
(dec130)ECHO
(dec130)SLEEP
(dec128)SADDR3
(dec131)ECHO
(dec131)SLEEP
(dec129)WAKE
(dec130)WAKE
(dec131)WAKE
Note: (hex80-83) is the same as (dec128-131). All lines must be terminated with
either a carriage return (dec13) or space character.
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