drive.doc

一个C style Assembler的source code

driver unit will transfer more precise information on the actual percent error.

   Communication with the driver unit may take place during the test.  This
makes it possible for the master unit to periodically poll the driver for its
current status and to determine when the driver is finished with a test.  The
driver unit may also receive an abort command from the master over the
communications line, telling it to stop the test, or telling it to change
speed or stop during jog mode.

   (C) Jog Mode
   When the driver receives the jog command, it will be set in the jog mode
for all the following tests until it next receives a different specification.
Each time a register is placed, the driver unit will automatically start the
jog process.
   The motor will accelerate up to a relatively fast speed.  Each time the
driver receives the change-speed command from the master, it will switch its
speed between fast and slow (1750 RPM and 500 RPM).  When it receives the
abort command, it will stop the motor.

(5) Communications and Commands
   (A) Overview.
   A RS-485 multidrop set-up is used to allow a master unit to communicate with
the driver, and possible several drivers in parallel.  Communications are run
with 9 bits, no parity, 1 data bit and at 9600 baud.

   At the driver unit, it is assumed that T0 will be driving the transmit
buffer.  When set, T0 enables transmissions over the RS-485, and when clear
transmissions are disabled.

   In general, at no time can more than one unit on a RS-485 line have its
transmission enabled.

   (B) Addresses and Address Matching.
   The 9th bit can be used by a master unit to distinguish between an address
and data.  If the unit had one master and 4 drivers, then each driver can be
given a different address, particularily, f7, fb, fd, and fe (hexadecimal).
In this setup there can also be one broadcast address (ff).
   When these addresses are represented in binary, the look like this:

               First Driver  f7: 1 1 1 1 0 1 1 1
               Second Driver fb: 1 1 1 1 1 0 1 1
               Third Driver  fd: 1 1 1 1 1 1 0 1
               Fourth Driver fe: 1 1 1 1 1 1 1 0
               Broadcast     ff: 1 1 1 1 1 1 1 1

A driver will respond to any addresses that "matches" its own address. A match
occurs with any address is sent out with 1's occurring in AT LEAST the positions
that the driver's address has 1's in.
   As an example that has nothing to do with the above, if the address to be
matched was 33 in hexadecimal (00110011 binary), then the following 16
addresses would match it:

      0 0 1 1 0 0 1 1   0 0 1 1 0 1 1 1   0 0 1 1 1 0 1 1   0 0 1 1 1 1 1 1
      0 1 1 1 0 0 1 1   0 1 1 1 0 1 1 1   0 1 1 1 1 0 1 1   0 1 1 1 1 1 1 1
      1 0 1 1 0 0 1 1   1 0 1 1 0 1 1 1   1 0 1 1 1 0 1 1   1 0 1 1 1 1 1 1
      1 1 1 1 0 0 1 1   1 1 1 1 0 1 1 1   1 1 1 1 1 0 1 1   1 1 1 1 1 1 1 1

which have hexadecimal values: 33, 37, 3b, 3f, 73, 77, 7b, 7f, b3, b7, bb, bf,
f3, f7, fb, and ff.  In the above cases, the only thing that matches address
f7, fb, fd, or fe is the address itself and ff.  This justifies calling ff the
broadcast address.

   When the 9th bit is set to 0, then it is assumed that data is being sent.
Only the units that have just been addressed will accept the data, the others
will simply ignore it.

   A master does not need an address, so each driver will only send data with
the 9th bit set to 0.  No driver ever sends an address.  The software for these
communication routines is contained in RX9.lib.

   (C) Polling
   A master unit can periodically poll each driver unit to determine when each
has just completed a test.  At that time, it will request more information on
the test results from the driver.

   (D) Command summary
   These are the possible commands that can be sent to the driver.  The
commands TEST, JOG, CHANGE, and ABORT can be sent with a broadcast address.
The others, STATUS, and DATA can only be send to individual addresses.
   The format of a command must be:

                   Address (9th bit set to 1),
                   Command (9th bit set to 0)

as described above.  The values of the commands are respectively:

                   0 ... TEST
                   1 ... JOG
                   2 ... CHANGE
                   3 ... STATUS
                   4 ... ABORT
                   5 ... DATA

The following is a summary of the commands:

   STATUS: To poll the driver's status:
      The driver will respond with two bytes:
              Speed ... the current speed of the motor in 25 RPM units,
                        represented iu Binary-Coded Decimal format.
              Status ... the byte containing the status flags:
                 Bit 0 = 1 if the motor is currently active, 0 else.
                 Bit 1 = 1 if the Client is in testing mode, 0 for jogging.
                 Bits 2 to 7 are all 0.
      The values of Status are thus:
             0 = Motor off.  Waiting to begin jog.  This is the initial state.
             1 = Motor running. Currently in jog mode.
             2 = Motor off.  Waiting to begin a test.
             3 = Motor running. Currently in a test.

      The Speed is represented as a Binary-Coded Decimal taking on values 00
      for (0 RPM), 01 (25 RPM), 02 (50 RPM), up to 70 (1750 RPM).

   DATA: To query the driver's measurement of register accuracy.
      The master unit should sent this command immediately after it detects
      a transition out of state 3.  The driver will respond by sending the
      following bytes:
              Sensors ... the number of sensors recorded (0, 1, or 2).
              Results ... the byte containing the results of the test:
                 Bit 0 = 1 if the test passed, 0 if it failed.
                 Bit 1 = 1 for a pulse match or over-count,
                         0 for a pulse-undercount.
                 Bits 2 to 7 are all 0.
              Percentage ... a absolute value of the percent error.

      The value of Results are thus:
             0 = Test failed.  Pulse under-count.
             1 = Test passed.  Measured pulse count < Calculated pulse count.
             2 = Test failed.  Pulse over-count.
             3 = Test passed.  Measured pulse count >= Calculated pulse count.

      A test is considered to have passed if it falls within the accuracy
      control limit (currently set at 0.4%).

      The last two items are only valid if the sensor count is two.  During a
      test, the Results and Percentage variables are set to 0.  Percentage is
      represented as a Binary-Coded-Decimal, taking on values 00h (0.0%),
      01h (0.1%), all the way up to 99h (9.9%).  Any percent error exceeding
      9.9% is truncated to 9.9%.

   TEST: To enable the test mode for the driver.
      Data will be sent to indicate the theoretical number of pulses the motor
      requires to rotate the register dial one full rotation.  The driver will
      use it to measure the register's accuracy against.  It will switch on
      Bit 1 obtained from the STATUS command.

      The pulse number is sent to the driver as a 3 byte integer with the lowest
      order byte first.

   JOG: To enable the jog mode for the driver.
      The driver will switch off Bit 1, as read in the STATUS command.

   CHANGE: To change the current jog speed.
      The driver responds by switching between fast jog and slow jog.  This
      only has effect in state 1 (jog mode active).

   ABORT: To abort a test, or to stop the jog mode. This only takes effect when
      Bit 0 of the STATUS command is on (motor active).

DATA is always responded to, but is only meaningful after a test has completed.
The values returned reflect the status of the last test run, or are meaningless
if no previous test has been run.  For obvious reasons, STATUS is also always
responded to.