While
there are a variety of options, the default mode for communicating
with a SmartMotor™ is serial RS-232 for the main port. Each SmartMotor™
is equipped with a secondary serial port named the AniLink port.
The AniLink port on a SmartMotor™ can be configured to communicate
with either RS-485 or I2C. The I2C connects SmartMotor™ peripherals
like LCD displays, I/O cards, etc., while the RS-485 will interface
bar code readers, light curtains, and other intelligent" peripherals
including other SmartMotors if desired.
To
maximize the flexibility of the SmartMotor™, these serial communications
ports are fully programmable with regard to bit-rate and protocol.
There
is a sixteen-byte input buffer for the primary RS-232 port and
another for the secondary RS-485 port. These buffers ensure that
no arriving information is ever lost, although when either port
is in data mode, it is the responsibility of the user program
within the motor to keep up with the incoming data.
By
default, the primary RS-232 channel, which shares a connector
with the incoming power, is set up as a command port with the
following default characteristics:
| |
Default: |
Other
Options: |
| Type: |
RS-232 |
RS-485
(w/adapter) |
| Parity: |
None |
Odd
or Even |
| Bit
Rate: |
9600 |
2400
to 38400 |
| Stop
Bits: |
1 |
0
or 2 |
| Data
Bits: |
8 |
7 |
| Mode: |
Command Data |
|
| Echo: |
Off |
On |
If
you do not have a cable, you can communicate with your SmartMotor™by
making the connections shown here and the SmartMotor™ will execute
the commands it receives.
Because
of the buffers on both sides there is no need for any hand shaking
protocol when commanding the SmartMotor™. Most commands execute
in less time than it would take to receive the next one. Still,
you should take some care to allow processes to complete, particularly
relatively slow processes like printing to a connected LCD display,
or executing a full subroutine. Since the EEPROM long term memory
is slow to write, the terminal software does employ two way communication
to regulate the download of a new program.
Daisy
chaining RS-232
Multiple
SmartMotors can be connected to a single RS-232 port as shown.
This
diagram could be expanded to as many as 100 motors. For independent
motion, however, each motor must be programmed with a unique address.
In a multi-motor system the programmer has the choice of putting
a host computer in control or having the first motor in the chain
be in control of the rest.
SADDR# Set motor to new address
The
SADDR# command causes a SmartMotor™ to respond exclusively to
commands addressed to it. The range of address numbers is from
1 to 100. Once each motor in a chain has a unique address, each
individual motor will communicate normally after its address is
sent at least once over the chain. To send an address, add 128
to its value and output the binary result over the communication
link. This puts the value above the ASCII character set, quickly
and easily differentiating it from all other commands or data.
The address needs to be sent only once until the host computer,
or motor, wants to change it to something else. Sending out an
address zero (128) will cause all motors to listen and is a great
way to send global data such as you would do to start simultaneous
motion in a chain. Once set, the address features work the same
for RS-232 and RS-485 communications.
Unlike
the RS-485 star topology, the consecutive nature of the RS-232
daisy-chain creates the opportunity for the chain to be independently
addressed entirely from the host, rather than have a uniquely
addressed program in each motor. Setting up a system this way
can add simplicity because the program in each motor can be exactly
the same. If the RUN? command is the first in each of the motor's
programs, the programs will not start upon power up. Addressing
can be worked out by the host prior to the programs being started
later by the host sending the RUN command globally.
SLEEP,
SLEEP1 Assert sleep mode
WAKE,
WAKE1 De-assert SLEEP
Telling
a motor to sleep causes it to ignore all commands except the WAKE
command. This feature can often be useful, particularly when establishing
unique addresses in a chain of motors. A 1 at the end of the command
specifies the AniLink RS-485 port.
ECHO,
ECHO1 ECHO input
ECHO_OFF,
ECHO_OFF1 De-assert ECHO
The
ECHO and ECHO_OFF commands toggle the echoing of data input. Because
the motors do not echo character input by default, consecutive
commands can be presented, configuring them with unique addresses,
one at a time. If the host computer or controller sent out the
following command sequence, each motor would have a unique and
consecutive address (~0 equals 128, ~1 equals 129, etc.).
~0SADDR1
~1ECHO
~1SLEEP
~0SADDR2
~2ECHO
~2SLEEP
~0SADDR3
~3ECHO
~0WAKE
Commanded
by the first motor, instead of a host, the same chain could be
addressed with the following sequence:
SADDR1
‘Address the first
ECHO ‘Echo
for host data
PRINT(#128,SADDR2",#13)
WAIT=10
‘Allow time
PRINT(#130,ECHO",#13)
WAIT=10
PRINT(#130,SLEEP",#13)
WAIT=10
PRINT(#128,SADDR2",#13)
WAIT=10
PRINT(#131,ECHO",#13)
WAIT=10
PRINT(#131,SLEEP",#13)
WAIT=10
PRINT(#128,SADDR3",#13)
WAIT=10
PRINT(#132,ECHO",#13)
WAIT=10
PRINT(#128,WAKE",#13)
WAIT=10
The
two communications ports have enormous flexibility. To select
from the vast array of options, use the OCHN command.
OCHN
|
Options: |
|
| Type: |
RS2,
RS4 |
RS-232
or RS-485 |
| Channel: |
0,
1 or 2 |
0=Main,
1=AniLink |
| Parity: |
N,
O or E |
None,
Odd or Even |
| Bit
rate: |
2400,
4800, 9600, 19200, 38400 baud |
|
| Stop
bits: |
0,
1 or 2 |
|
| Data
bits: |
7
or 8 |
|
| Mode: |
C
or D |
Command
or Data |
For
the AniLink port in I2C mode use IIC for the type, 2 for the channel
and either 400 or 1000 for the bit rate. Use any legal value for
the other parameters as place holders. They will otherwise be
ignored. Here is an example of the OCHN command:
OCHN(RS2,0,N,38400,1,8,D)
If
the primary communication channel (0) is opened as an RS-485 port,
it will assume the RS-485 adapter is connected to it. If that
is the case the UG pin in the same connector is assigned the task
of directing the adapter to be in Transmit or Receive mode in
accordance with the motor's communication activity.
CCHN(type,channel) Close
a communications channel
Use
the CCHN command to close a communications port when desired.
BAUD# Set BAUD rate of main port
The
BAUD# command presents a convenient way of changing only the bit
rate of the main channel. The number can be from 2400 to 38400
bps.
PRINT(
), PRINT1( ) PRINTA-PRINTH Print
to RS-232 or AniLink channel
A
variety of data formats can exist within the parentheses of the
PRINT( ) command. A text string is marked as such by enclosing
it between double quotation marks. Variables can be placed between
the parentheses as well as two variables separated by one operator.
To send out a specific byte value, prefix the value with the #
sign and represent the value with as many as three decimal digits
ranging from 0 to 255. Multiple types of data can be sent in a
single PRINT( ) statement by separating the entries with commas.
Do not use spaces outside of text strings because SmartMotors
use spaces as delimiters along with carriage returns and line
feeds.
The
following are all valid print statements and will transmit data
through the main RS-232 channel:
| PRINT(Hello
World") |
‘text |
| PRINT(a*b) |
‘exp. |
| PRINT(#32) |
‘data |
| PRINT(A",a,a*b,#13) |
‘all |
PRINT1
prints to the AniLink port with RS-485 protocol while PRINTA
prints to the AniLink port using I2C protocol in such a way as
to send data to an LCD display or standard parallel input line
printer (with a DIO-100 card on the AniLink bus).
SILENT,
SILENT1 Suppress PRINT() outputs
TALK,
TALK1 De-assert silent mode
The
SILENT mode causes all PRINT( ) output to be suppressed. This
is useful when talking to a chain of motors from a host, when
the chain would otherwise be talking amongst itself because of
executing programs containing PRINT( ) commands.
! Wait for RS-232 char. to be received
A
single exclamation mark will cause program execution to stop until
a character is received. This can be handy under certain circumstances
like debugging a program in real time.
a=CHN0,
a=CHN1 RS-485 communications error flags
The
CHN0 and CHN1 variables hold binary coded information about the
historical errors experienced by the two communications channels.
The information is as follows:
| Bit |
Value |
Meaning |
| 0 |
1 |
Error? |
| 1 |
2 |
|
| 2 |
4 |
|
| 3 |
8 |
|
| 4 |
16 |
|
| 5 |
32 |
|
| 6 |
64 |
|
| 7 |
128 |
|
A
subroutine that printed the errors to an LCD display would look
like the following:
C911
IF CHN0
‘If CHN0 != 0
DOUT0,1 ‘Home LCD cursor
IF CHN0&1
PRINTA(ERROR1")
ENDIF
IF CHN0&2
PRINTA(ERROR2")
ENDIF
IF CHN0&4
PRINTA(ERROR3")
ENDIF
IF CHN0&8
PRINTA(ERROR4")
ENDIF
CHN0=0 ‘Reset CHN0
ENDIF
RETURN
a=ADDR Motor's self address
If
the motor's address (addr) is set by an external source, it may
still be useful for the program in the motor to know what address
it is set to. When a motor is set to an address, the ADDR variable
will reflect that address from 1 to 120.
Getting
data from a COM port
If
a com port is in Command Mode, then the motor will simply respond
to arriving commands it recognizes. If the port is opened in Data
Mode, however, then incoming data will start to fill the 16 byte
buffer until it is retrieved with the GETCHR command.
a=LEN Number
of characters in RS-232 buffer
a=LEN1 Number
of characters in RS-485 buffer
a=GETCHR Get
character from RS-232 buffer
a=GETCHR1 Get
character from RS-485 buffer
The
buffer is a standard FIFO (First In First Out) buffer,. This means
that if the letter A is the first character the buffer receives,
then it will be the first byte offered to the GETCHR command.
The buffer exists to make sure that no data is lost, even if your
program is not retrieving the data at just the right time. Two
things are very important when dealing with a data buffer for
the protection of the data:
1) Never GETCHR
if there is no CHR to get.
2) Never let the
buffer overflow.
The
LEN variable holds the number of characters in the buffer. Your
program must observe that the LEN is greater than zero before
issuing a command like: a=GETCHR. Likewise, you will need to arrange
your application such that overall, you will be pulling data out
of the buffer faster than it comes in.
Being
able to configure the communication ports for any protocol as
well as being able to transmit and receive data allows the SmartMotor™
to interface with a vast array of RS-232 or RS-485 devices. Some
of the typical devices that would interface with SmartMotors
over the communication interfaces are:
1) Other SmartMotors
2) Bar Code Readers
3) Light Curtains
4) Terminals
5) Printers
The
following is an example program that repeatedly transmits a message
to an external device (in this case another SmartMotor™) and then
takes a number back from the device as a series of ASCII letter
digits, each ranging from 0 to 9. A carriage return character
will mark the end of the received data. The program will use that
data as a position to move to.
A=500
‘Preset Accel.
V=1000000
‘Preset Vel.
P=0
‘Zero out Pos.
O0
‘Declare origin
G
‘Servo in place
OCHN(RS2,0,N,19200,1,8,D)
PRINT(RP",#13)
C0
IF LEN ‘Check for
chars
a=GETCHR ‘Get char
IF a==13
‘If carriage ret.
G ‘Start motion
P=0 ‘Reset P to zero
PRINT(RP",#13) ‘Next
ELSE
P=P*10 ‘Shift P
a=a-48 ‘Adjust for ASCII
P=P+a ‘Build P
ENDIF
ENDIF
GOTO0
‘Loop forever
The
ASCII code for zero is 48. The other nine digits count up from
there so the ASCII code can be converted to a useful number by
subtracting the value of 0 (ASCII 48). The example assumes that
the most significant digits will be transmitted back first. Any
time it sees a new digit, it multiplies the previous quantity
by 10 to shift it over and then adds the new digit as the least
significant. Once a carriage return is seen (ASCII 13), motion
starts. After motion is started, P (Position) is reset to zero
in preparation for building up again. P is buffered so it will
not do anything until the G command is issued.
