µSR User Facilities
LTC Temperature Controller Set-up Procedure
This page describes the set up of a cryostat for operation with the
LTC controller and the SET_CONDUCTUS program.
Philosophy
With the present system, we try to achive maximum flexibility in setting up and
operating any cryostat/controller combination. For proper operation, four parts
need to be set up correctly:
- Cryostat fittet with one or more Control Sensors and Heaters
- LTC Controller fitted with Temperature Sensor Calibration Tables and PID Tables
- LTC Controller Memory Look-Up Table reflecting the LTC memories in a text file
for reference to the SET_CONDUCTUS program.
- Sample Holders Look-Up Table defining in a text file the way sensors and heaters
are combined to one or more control loops.
When initializing the system via SET_CONDUCTUS, the program presents you with
the cryostats/sample holders and their respective control modes from the
Sample Holders Look-Up Table for selection and the PID tables from the
LTC Controller Memory Look-Up Table for assignment to the selected control loops.
1. Sensor Calibration Tables
1.1 Sensor Calibration Tables Archive
Located on NT Domain LMU group disk
\\PSI10\G_1610\Temperature Sensors
A separate directory for every sensor class exists:
CGR1 Carbon-Glass Resistance Sensors
CX10 Cernox Resistance Sensors
PT1 Platinum-100 Resistance Sensors
STANDARD Standart Curves (e.g. Standard Curve 10 for Silicon Diode Sensors)
TG120 GaAlAs Diode Sensors
Decommissioned (dead, burned, etc.) sensors are stored in the respective [.OLD]
subdirectories.
For each Calibration Table, two ASCII file versions are available:
.TAB Raw Table as supplied by manufacturer
.LTC Table for download to LTC controller with SET_CONDUCTUS,
fitted with all necessary parameters and control characters.
2. LTC Controller
If group logical CONDUCTUS_USER is defined as
$ DEFINE /GROUP CONDUCTUS_USER MASTER
calibration tables may be downloaded, cleared or shown interactively when
Modify/Set Device/Conductus is selected in the MODAS run control menu.
$ DEASSIGN /GROUP CONDUCTUS_USER
hides this functionality.
2.1 Installing Temperature Calibration Tables
2.1.1 Downloading Temperature Calibration Tables
- Make sure, the .TAB versions for all Calibration Tables to be downloaded
reside in the ED:[DAT.LTC] directory of the area machine. If necessary,
transfer them from the Calibration Table archive (see 1.).
- The LTC controller accepts a maximum of 16 User Calibration Tables.
Make sure, enough free memory slots are available. User Calibration Tables may be
cleared from LTC memory. The indices of the Calibration Tables following the deleted
table in the list will be decreased. When a User Calibration Table is downloaded
it will always be appended at the end of the list.
- Modify the file LTC_'Serial Number'_DWNLD.COM in
ED:[DAT.LTC] to make it download the Tables needed. And ONLY those.
See an example of a download command procedure.
- Run the LTC_'Serial Number'_DWNLD.COM command procedure.
- It is necessary to manually check each one of the downloaded tables on the LTC.
Otherwise the table will not be activated and may therefore not be used.
2.1.2 Updating the LTC Look-Up Table
- Update the appropriate LTC Look-Up Table LTC_'Serial Number'.TAB
in ED:[DAT.LTC] to make it reflect precisely the calibration tables
memory list on the LTC controller.
2.1.3 Updating the Sample Holders Look-Up Table
- If you have replaced a control sensor:
Update the appropriate Control Mode(s) for your cryostat/sample holder in
ED:[DAT.LTC]SAMPLE_HOLDERS.TAB. Replace all old Sensor Names with the new
Name as it appears on the LTC User Calibration Tables memory list.
- If you have added a control sensor and/or heater:
Extend the Control Modes for your cryostat/sample holder in
ED:[DAT.LTC]SAMPLE_HOLDERS.TAB.
2.2 Installing PID Tables
2.2.1 Creating PID Tables
2.2.2 Downloading PID Tables
Download your table using the DCL command
@ED:[COM]SET_CONDUCTUS DOWNLOAD PIDTABLE 'PID Table Name'.PID 'PID Table Index'
Example:
@ED:[COM]SET_CONDUCTUS DOWNLOAD PIDTABLE TEST_PID.PID 1
downloads the PID Table ED:[DAT.LTC]PID_TABLE.PID as PID Table 1 to the
LTC controller.
Verify the PID table values stored in the LTC controller memory before
setting the controller to control mode the first time!
2.3 Setting the Filter Time
Remember to set the appropriate Filter Time for your system manually at the LTC controller
(Setup - Display - Setup Input Filter).
2. LTC Controller Memory Look-Up Table
The LTC Controller Memory Look-Up Table LTC_'Serial Number'.TAB in
ED:[DAT.LTC] reflects for every single LTC controller the contents of the
Calibration Tables and PID Tables memory and some other parameters like the device
GPIB address.
See an example of a LTC Controller Memory Look-Up Table.
When installing a cryostat sytem, make sure the Memory Look-Up Table for the LTC controller
in use is located in ED:[DAT.LTC] of your area machine and precisely reflects
the contents of the memories.
3. Sample Holders Look-Up Table
The Sample Holders Look-Up Table ED:[DAT.LTC]SAMPLE_HOLDERS.TAB defines all
existing cryostats/sample holders and their respective Control Modes in one file.
It containes:
- The Name of a Cryostat/Sample Holder
- If the system is operated in single (single_loop) or
two-loop mode (two_loop).
- The Sensor Location Name (e.g. Diffuser_Sensor)
- The Sensor Name of the Sensor allocated to a Sensor Location (e.g. CX1050SD_X03458)
- To which LTC channel a sensor is assigned.
- First line: Channel 1 = Heater Output
- Second line: Channel 2 = Analog Output
- Exception: If the keyword analog is given on the first line as fourth column,
Analog Output is assign to Channel 1. If the keyword heater is specified on the
second line as forth parameter, Heater output is assigned to channel 2.
- If keyword A=pid_table_name or H=pid_table_name is specified as
fourth parameter, pid_table_name will be assigned to H(eater) or
A(nalog), respectively, during LTC setup.
See an example of SAMPLE_HOLDERS.TAB.
When installing a cryostat sytem, make sure SAMPLE_HOLDERS.TAB is
located in ED:[DAT.LTC] of your area machine and up to date.
3. Control Modes
3.1 Updating a Control Mode
This applies if you have replaced a control sensor.
3.1.1 Updating the Sample Holders Look-Up Table
Update the appropriate Control Mode for your cryostat/sample holder in
ED:[DAT.LTC]SAMPLE_HOLDERS.TAB.
3.2 Creating a new Control Mode
This applies if you have introduced an additional control sensor and/or heater or
if you want to pair a control sensor with a different heater.
3.2.1 Extending the Sample Holders Look-Up Table
Extend the Control Modes for your cryostat/sample holder in
ED:[DAT.LTC]SAMPLE_HOLDERS.TAB
1. Setting up a cryostat/controller combination
2. After introducing a new sensor or replacing a sensor
2.1 Updating the Sample Holders Look-Up Table
2.2 Downloading the appropriate Calibration Table
2.3 Updating the LTC Look-Up Table
Appendix A: Calibration Table File Names and Sensor Names
Note that Calibration Table File Names and Sensor Names are not identical.
Sensor Names, as they appear in the .LTC versions of the Calibration Table Files,
on the LTC controller and in the SAMPLE_HOLDERS.TAB Look-up Table carry
the package type as additional parameter, if applicable.
The Calibration Table File Names follow the scheme:
'Short Sensor Type Code'_'Serial Number'.'File Type'
The Sensor Names follow the scheme:
'Full Sensor Type Code''Package Type Code'_'Serial Number'
Sensor Type Codes
Short Full Type
CGR15 CGR1500 CGR-1-500
CGR11 CGR11000 CGR-1-1000
CGR12 CGR12000 CGR-1-2000
CX103 CX1030 CX-1030
CX105 CX1050 CX-1050
PT111 PT111 PT-111
TG120 TG120 TG-120
See manufacturer's literature for specifications.
Package Type Code
CU
LR
P
SD
See manufacturer's literature for specifications.
Sensor Serial Number
Sensor Serial Number, typically starting with a one-letter code followed by
4- to 5-digit numbers.
Sensor Class Code Typical no. of digits following
CGR C 5
DT D 5
PT P 5
CX X 5
TG-120 none 4
File Type
.TAB Raw Table as supplied by manufacturer
.LTC Table for download to LTC controller, fitted with all necessary
parameters and control characters.
Most Calibration Table files are created by means of OCR from the hard copy of
the manufacturer's calibration table and have been carefully checked for
errors. However, typos are not to 1O0% excluded...
xavier.donath@psi.ch
µSR Home Page