DESCRIPTION

The Newport Agilis AG-UC2 and AG-UC8 piezo controller modules are both supported by spec. The Agilis AG-UC2 uses a USB interface while the AG-UC8 can use either a serial or USB interface.

The AG-UC2 controller handles two axes which can be operated simultaneously. The AG-UC8 has four channels, each of which functions as a two-axis AG-UC2 for a total of eight axes. However, only one of the two-axis channels in the AG-UC8 can be active at a time. The settings and current positions for the channels are not maintained in the AG-UC8 when switching from one two-axis channel to the next. spec's AG-UC8 support handles the multiplexing transparently, making it is possible to specify new positions for all eight actuators on the AG-UC8 in one command. spec will take care of synchronizing parameters and moving the channels in sequence.

CONFIGURATION

Select "Newport Agilis (Serial)" as the controller type for both the AG-UC2 and the AG-UC8, even when using the USB connection. The Agilis models use an FTDI USB interface chip that is recognized by drivers available on both Linux and Mac OS X. The kernel driver makes the device appear as a serial interface to spec.

On Linux, the standard ftdi_sio kernel module is required. Recent Linux kernels include recognition of the Agilis USB device IDs in the ftdi_sio driver. For older kernels, edit a file in /etc/module.d/ (a file could be created named local.conf, for example) to add the line:

options ftdi-sio product=0x3000 vendor=0x104d

On OSX, the VCP driver available at the ftdichip.com must be installed. The Newport Agilis USB vendor and product IDs need to be added to the kernel extension Info.plist file as explained in the FTDI Technical Note 105 available at the FTDI website. Contact CSS for assistance, if needed.

If using a direct serial connection to the AG-UC8, select a baud rate of 115200. If connecting the AG-UC2 directly or using the USB port on the AG-UC8, the baud rate should be 921600.

In some configurations, the serial communication between spec and the Agilis may need to be slowed. Non-standard optional parameters named "wdelay" and "rdelay" can be set from the Devices screen of the configuration editor. These parameters set a delay time before write commands to the Agilis and before reading replies, respectively. Units for the parameters are seconds. A delay of 0.010 seconds has been needed in at least one installation. spec limits the delay to a maximum of 0.5 seconds. Type p from the Devices screen to create and edit nonstandard optional controller parameters. The delays can only be set in the config file.

The step amplitude associated with the controller's SU command can be configured as a nonstandard optional parameter for each motor from the Motor screen of spec's hardware configuration editor. There are separate parameters for positive and negative movements, named "amplitude+" and "amplitude-".

An additional nonstandard optional parameter named "PA_target" can be configured to set the target position used with the home command, as explained in the next section.

Type p from the Motor screen to create and edit nonstandard optional motor parameters. All three parameters can also be changed and examined within spec using motor_par(), whether or not they are added to the config file.

HOMING

There are two types of home search implemented in spec for the Agilis controllers. The chg_dial(mne, "lim+") and chg_dial(mne, "lim-") commands will use the controller's MV command to send the actuator to the positive or negative limit switches. Of course, the command will only work with stages that have limit switches. The movement can be done at four possible speeds, which are set using the home_method optional motor parameter as follows:

1	5 steps/sec at defined step amplitude
2	100 steps/sec at maximum step amplitude
3	1700 steps/sec at maximum step amplitude
4	666 steps/sec at defined step amplitude

If the home_method parameter is not set, method 4 will be used.

The second home search uses the PA command and is initiated with the "home", "home+" and "home-" options to chg_dial(). These are the options used with chg_dial() within spec's standard home macro. All three options produce the same action on the Agilis.

With the PA command, the controller first moves the stage to the positive limit. The stage is then moved to the negative limit while steps are counted. The stage is moved back to the positive limit, then moved the number of steps needed to position the stage at a specified percentage of the total distance. That percentage is taken from the parameter "PA_target", which can have a value from 0 to 100, with a precision of one part in a thousand. If unset, a value of 50 is used.

Note, the PA procedure can take a couple of minutes to perform. However, the search can be interrupted with ^C.