DESCRIPTION

The Physik Instrument E-712 is a modular digital piezo controller available in 3- and 6-channel configurations. spec supports the controller's serial and Ethernet interfaces.

Use the Device screen of spec's hardware configuration editor, the edconf program (normally run from the config macro), to select the controller type and to assign the interface parameters:

Motor and Counter Device Configuration (Not CAMAC)

MOTORS     DEVICE ADDR <>MODE NUM                       <>TYPE
   YES /dev/ttyS1   <> 115200   3 PI E-712 Controller (Serial)
   YES   E712host               3 PI E-712 Controller (Socket)

For the socket configuration, the DEVICE column contains an IP address or resolvable host name. A optional port number can be specified as in 192.168.1.123:50000. If not specified, the default port of 50000 is used. (That is currently the only port supported by the controller.)

The piezo stages supported by the E-712 can be operated in servo or open-loop mode. When spec makes a connection to the controller, spec queries the current setting of each stage. If in open-loop mode, spec uses the SVA command to move the motor and the VOL? command to read the position. In servo mode, the commands MOV and POS? are used. The mode can be changed using the "servo_mode" option to motor_par(). The "servo_mode" parameter can be also added to the hardware config file as a nonstandard optional parameter, as described below.

When in open-loop mode, there is no status available from the controller as to whether the move has completed or if the stage is on target, so moves are considered complete virtually immediately after sending the move command. Configure the settle time and dead band parameters, described below, if delays are needed.

On the Motor screen of the configuration editor, choose the controller type as PI_E712. An appropriate value for the steps-per-degree parameter is 1e6. The slew rate, base rate and acceleration time are not used by spec for this controller. However, some of the standard optional motor parameters, reached by typing a lower case m from the main motor configuration screen, are recognized and may be useful.

To configure a settling time at the end of each move, set the optional parameters DC dead band ("dc_dead_band") and DC settle time ("dc_settle_time"). If those parameters are configured, after the controller reports the move is complete, spec will continue to wait an additional time given by the settle time before reporting the move complete. In addition, spec will also wait for the difference between the target position and the actual position to be within the dead band. If the motor doesn't settle within five seconds, spec reports an error. Note, the dead band and settling time parameters set here are not associated with the controller's internal on-target tolerance parameter (0x07000900) and settling time parameter (0x07000901).

Additionally, the read-back slop parameter ("slop") and/or the hardware read-mode parameter ("read_mode") can be used as needed to suppress position discrepancy messages. If the slop parameter is set to some number of steps, spec will not report position discrepancies smaller than that value and will instead silently accept the reported hardware value as the position. The read-mode parameter controls how often the position is read from the hardware and can also tell spec to always accept the reported hardware value, no matter how large. spec normally assumes a motor is at its last position. If the PREMOVE read-mode option is set, spec will always read the hardware before moving the motor. If the ALWAYS option is set, spec will read the hardware whenever the get_angles command is run from user level. If the NO QUERY option is set, spec will always assume the hardware is correct and not query the user as to how to resolve the discrepancy if the returned hardware position differs from the current software position. If the NO QUERY option is set, the "slop" parameter is not used.

PARAMETER CLASSES

The E-712 has hundreds of parameters which are described in more detail in the Physik Instrumente user manual for the controller. Physik Instrumente assigns the parameters to nine classes, each associated with a particular function, as follows:

Servo	logical axis
Input	input channel
Output	output channel
System	whole system
DDL	Dynamic Digital Linearization
StdIF	standard interfaces
WaveGen	wave generator
Recorder	data recorder
FW_Update	firmware

For any given class, there are values for a varying number of channel or index identifiers. For example, there are as many Servo indices as there are logical axes. The number of Input, Output and FW_Update indices depends on the hardware model. Some System parameters have only one index while the number of indices for other System parameters depends on the hardware model. There is only one index for DDL, StdIF, WaveGen and Recorder parameters for all hardware models.

Each parameter is associated with a unique hexadecimal number code, an axis (or index) identifier number from 1 to the maximum number of indices, a class as listed above, an attribute that indicates what privileges are need to modify the parameter and a description of the parameter. spec only allows modification to unprotected parameters. For other parameters, the controller requires a password to make changes.

PARAMETER DISPLAY

Various parameter attributes can be displayed with options to the motor_par() function, as described below. For example the following displays non-zero parameters associated with axis 1 of the controller:

SPEC.1> p motor_par(z, "dump_servo")
Servo parameters:
           Range Limit max  [1] (0x07000001) : 50
      Servo Loop Slew-Rate  [1] (0x07000200) : 5000
       Open Loop Slew-Rate  [1] (0x07000201) : 1e+06
         Servo-loop P-Term  [1] (0x07000300) : 0.031
         Servo-loop I-Term  [1] (0x07000301) : 0.000363552
    Position from Sensor 1  [1] (0x07000500) : 0.5
    Position from Sensor 2  [1] (0x07000501) : 0.5
                 Axis Name  [1] (0x07000600) : Z
                 Axis Unit  [1] (0x07000601) : um
                       ...

The following options are available. Note, the argument is case insensitive - upper and/or lower case letters can be used interchangeably. All commands are directed to the controller associated with motor mne. Only commands in the Servo class are automatically associated with the particular motor axis mne. Some forms of the commands suppress displaying parameters that have a value of zero for ease of viewing.

motor_par(mne, "dump")

Display all parameters from all classes.

motor_par(mne, "dump_all")

Display all parameters from all classes, but suppress printing parameters with values of zero.

motor_par(mne, "dump_Servo")

Display non-zero parameters associated with the motor mne.

motor_par(mne, "dump_Servo", n)

Display all parameters associated with the axis n.

motor_par(mne, "dump_Input")

Display non-zero parameters associated with all input channels.

motor_par(mne, "dump_Input", n)

Display all parameters associated with input channel n.

motor_par(mne, "dump_Output")

Display non-zero parameters associated with all output channels.

motor_par(mne, "dump_Output", n)

Display all parameters associated with output channel n.

motor_par(mne, "dump_System")

Display non-zero system parameters.

motor_par(mne, "dump_System", n)

Display all system parameters with index n.

motor_par(mne, "dump_FW_Update")

Display all non-zero firmware-related parameters.

motor_par(mne, "dump_FW_Update", n)

Display all firmware-related parameters with index n.

motor_par(mne, "dump_StdIF")

Display all non-zero interface-related parameters.

motor_par(mne, "dump_DDL")

Display all non-zero dynamic digital linearization parameters.

motor_par(mne, "dump_WaveGen")

Display all non-zero wave generator parameters.

motor_par(mne, "dump_Recorder")

Display all non-zero recorder parameters.

INDIVIDUAL PARAMETERS

Individual parameters can be displayed or set using the hexadecimal parameter code. A particular parameter code may be associated with more than one parameter, as differentiated by index number. For Servo class parameters, the index number can come from the motor number. For all classes of parameters, the index number can be specified using a string in the form "hexpar:index". For example, to print the stage type (a System class parameter) associated with axis 2, use:

p motor_par(mne, "0x0f000100:2")

For Servo class parameters, if the index number is missing, it will be derived from the motor number. If the index count for the parameter is one, no index need be given. Otherwise, an error message is displayed. If an index is not needed, the parameter number does not need to be passed as a string. For example, to print the axis name, the following works:

p motor_par(mne, 0x07000600)

Parameter values are set by supplying the value in the third argument:

motor_par(mne, 0x7000200, 5000)

The abovet sets the servo loop slew-rate for motor mne to 5000.

NONSTANDARD OPTIONAL PARAMETERS

Nonstandard optional parameters are hardware parameters that are not part of spec's device-independent hardware support. The parameters can be recognized by spec's device-dependent support, as documented for the particular controller.

From the spec hardware configuration editor, nonstandard optional parameters are created by typing the p command when a device row or motor column contains the highlighted cell. For the E-712, parameters can be associated either with the controller unit on the Devices screen or with individual motors on the Motor screen.

Nonstandard optional parameters recognized by the E-712 support are the parameter "servo_mode" and all the hexadecimal parameter codes recognized by the controller. The "servo_mode" parameter and hexadecimal parameters in the Servo class are associated with an individual motor axis. The rest of the hexadecimal parameters are associated with the controller entry.

The configuration screen for nonstandard optional parameters for a motor channel looks like this (reached by typing the p command from the main Motor screen):

Custom Parameters for Motor "Xrot" (xrot)          2/2 configured

NAME                      VALUE
servo_mode                1
0x7000300                 .031

Type p when done               Type ? and H for help, ^C to quit

For the controller entry on the Devices screen, the nonstandard optional parameter screen looks like this:

Custom Parameters for "PI E-712 Piezo Controller"  6/6 configured

NAME                      VALUE
0x02000100:1                  1
0x02000100:2                  1
0x02000101:1                  1
0x02000101:2                  1
0x02000102:1                 16
0x02000102:2                 16

The nonstandard optional parameters can also be accessed via the motor_par() command, although if the parameters are given values in the config file, the config file values will be reprogrammed when the hardware is reinitialized on startup or with the reconfig command.

PARAMETER ACCESS VIA motor_par()

The nonstandard optional parameters may be accessed via motor_par(), whether or not the parameters have been entered into the config file, as described above. When using motor_par() to access parameters not associated with a particular axis, such as all of the hexadecimal parameters that are not in the Servo class, the mne argument simply identifies the controller to which the parameter belongs.

Note, values for nonstandard optional parameters associated with the controller device in the config file cannot be modified using motor_par(). Their values can only be changed through the configuration editor.

motor_par(mne, "servo_mode")

Returns one or zero, indicating whether servo mode is on or off for the specified axis.

motor_par(mne, "servo_mode", 1|0)

Sets or clears servo motor for motor mne.

motor_par(mne, hexpar)

Returns current value for hexpar. If associated with the Servo class, returns for motor mne. Otherwise, if only one "item" associated with the parameter, returns that item. Otherwise, returns an error.

motor_par(mne, "hexpar:index")

Returns current value for hexpar associated with item index. Item numbers start at one.

motor_par(mne, hexpar, value)

Set value for hexpar. If associated with the Servo class, sets value for motor mne. Otherwise, if only one "item" associated with the parameter, sets that item. Otherwise, returns an error.

motor_par(mne, "hexpar:index", value)

Set value for hexpar associated with item index. Item numbers start at one.

COMMAND PASS THROUGH

Command pass through is available using the following functions. Command pass through should be used with caution to avoid interfering with the built-in programming commands spec sends to the controllers.

motor_par(mne, "send", cmd)

Sends the string cmd to the channel associated with mne.

motor_par(mne, "read", cmd)

Sends the string cmd to the channel associated with mne, as above, and returns a string containing the response.

motor_par(mne, "usend", cmd)

Sends the cmd to the controller associated with mne. Unlike the "send" option above, no channel address is added to the string.

motor_par(mne, "uread", cmd)

Sends the string cmd to the controller associated with mne, as above, and returns a string containing the response. Again, unlike the "read" option above, no channel address is added to the string.