HOST - A personal computer with terminal software,
i.e. Windows
Terminal or BitComm .etc. and a RS-232 serial port.
COMMUX - A device used to interface between the HOST RS-232 serial line and a RS- 485 multidrop network.
CRYONET - The name we use for the RS-485 multidrop wire network used for communication between the COMMUX, HLD’s, and the GASMAN.
HLD - The Helium Level Detector used to measure the liquid level in a helium dewar.
SLD - The Stationary helium Level Detector used to measure the liquid level in a non-moving helium dewar or experimental cryostat dewars.
GASMAN - A device used to read the helium gas flow meters. The first type to go in service was one unit that read up to 24 individual gas meters. The second type to go into service was designed to be one unit per gas flow meter.
The HOST computer is connected to the COMMUX through the HOST serial port. The COMMUX is connected to both the HOST and through the CRYONET to the HLD’s and the GASMAN. With the addition of an ethernet card to the HOST computer and Remote control software it is possible to communicate with the COMMUX over the ethernet. We used this method to expand the helium monitoring system to other buildings on this campus.
Helium Level Detectors on transport dewars: (#1-39)
HLD 1 is on a 100 liter transport dewar. Started February, 1994. HLD 1 has been on dewars number 4 and number 1 and has been modified and adjusted many times. It and HLD 2 have been used to do most of the development work on the level detectors. The battery had to be replaced once.
HLD 2 is on a 100 liter transport dewar. Started March, 1994 HLD 2 has had all of the same modifications as HLD 1. The battery has also been replaced.
HLD 3 is on a 100 liter transport dewar. Started May 19, 1995. HLD 3 was modified to be identical to HLD 1 & 2 when it was first powered up. The probe on HLD 3 has had its cable mashed and the top of the probe tube bent so that there might have been an intermittent short in the cable. A new probe was built and installed. HLD 3 has had to be reset and recalibrated for the new probe.
HLD 4 is on a 100 liter transport dewar. Started August, 1995. HLD 4 has had its circuits modified to match HLD1. The probe connected to HLD 4 was very difficult to get to work without heater shorting. Recently the heater on this probe has had an open circuit. I repaired the heater, but now the level conversion table does not match a thump of the dewar. The heater repair should not have made a difference in the level conversion table. A new probe was built and installed.
HLD 5 direct mount on the squat 100.
HLD 6 started December 21, 1998 when it was mounted on a 60 liter dewar on a lift.
HLD 7 direct mount on
a 100.
HLD 8 direct mount on a 100.
HLD 9 was on a 300 liter transport dewar. Started September 5, 1995. HLD 9 matches the circuits on HLD 1. This HLD has the first probe made from scratch using the new wires purchased and designed for this dewar. Have not had negative feedback about this HLD yet. This dewar sat in MicroKelvin much of the time. HLD 9 has had its battery discharge (display BATTERY LOW) twice since it started operation. The first time the battery voltage went so low that the level could not be read using the HLD and the LCD went blank. The second time the battery voltage did not go as low but, accurate liquid levels could not be read until the battery was charged above the minimum 12 volt value. HLD 9 was renamed to HLD 15. HLD 20 was converted to HLD 9 on April 21, 2000.
HLD 10 direct mount on a 100.
HLD 11 is now mounted on a 60 liter dewar, #11. Started April, 30 1997 and used for a short while and was taken out of service for no apparent reason from January 23 1998 until December 1998 . It has been in service since then.
HLD 12 Temporarily
used for a small
research cryostat in B158.
HLD 13 direct mount
on a 100.
HLD 15 is mounted on a 250 liter transport dewar. Started on xxxxxxx. HLD 16 is mounted on dewar 16. HLD 16 has gone dead on several occasions. The usual situation is to find HLD 15 with the LCD showing all black blocks. It will sometimes respond to the CRYONET commands, but not to the keyboard. HLD 16 has also had this same problem. It was originally thought that this problem is related to the fiber optic link between Williamson Hall and the MicroKelvin laboratory. We now think that it is caused by static electrical discharges on the HLD box.
HLD 16 is mounted on a 250 liter transport dewar. Started on January 24, 1996. HLD 16 is mounted on dewar 16. HLD 16 has gone dead on several occasions. The usual situation is to find HLD 16 with the left half of the LCD black. It will respond to the CRYONET commands, but not to the keyboard. HLD 15 has also had this same problem.
HLD 17 direct mount on a 100 on a lift.
HLD 18 direct mount on a 100.
HLD 19 direct mount on a 100.
HLD 20 was mounted on the UK2 cryostat. Started on August 17, 1995. HLD 20 was mounted in UK2 and was powered by a wall transformer. Level readings can not be made using HLD 20 unless the AC power is on. HLD 20 was not connected to the CRYONET and I can only access this HLD by removing it from the screen room and bringing HLD 20 to the work bench. HLD 20 was being used for code development and testing in the Electronics Shop. It was converted to HLD 9 on April 21, 2000.
HLD 23 direct mount on a 100.
HLD 24 direct mount on a 100.
HLD 25 direct mount on a 250.
HLD 26 direct mount
on a 250 - For a while
#51 was used on dewar #26 and now HLD 98 (was used for developement in
the Eshop) has been converted to HLD 26.
Stationary Helium Level Detectors: (#40-59)
SLD 40 was the prototype SLD mounted on a experimental cryostat dewar in Rm. 106 Williamson Hall. Started on March 3, 1997. It is connected to the CRYONET through a fiber link because it is in a "low noise" EMF shield room in the Ihas lab in Williamson.
SLD 41 is mounted on an experimental cryostat dewar in the MicroKelvin laboratory in Bay #1. The level calibration appears to be accurate but still requires a 20 liter offset.
SLD 42 is mounted on an experimental cryostat dewar in the MicroKelvin laboratory in Bay #2. Started February 17, 1999. Calibrating the probe to the actual helium level in the dewar was adversely effected by the local operator expert in the lab and so the calibration has a 50 liter offset and does not match the level changes as well is it could and should.
SLD 43 is mounted on an experimental cryostat dewar in the MicroKelvin laboratory in Bay #3.
SLD 44 was in the
electronics shop and was
being used for code development.
SLD 45 Cryostat in
B124
SLD 46 Unused
SLD 47 It is now on SHIVA in NPB B39.
HLD 50 NPB B135 Meisel. Was Temporarily #26
HLD 51 NPB B135
Meisel.
Stationary helium Level Detectors on Storage dewars: (#60-64)
SLD 60 is mounted on the 1000 liter storage dewar in the Cryogenic Services facility in the New Physics building. It began life as SLD 61. It was mounted on the 1000 liter storage dewar in the basement of Williamson Hall. It was started on April 2, 1996. Because the HLD’s can only display values between 0 and 255 one must multiply the displayed value by ten to get the actual liquid level. There was a problem with this HLD when the liquefier is running the liquid level inside this dewar is so turbulent that the level could not be measure using the HLD. It has been corrected. Level readings can now be taken at all times reliably. This HLD has a modified routine used to measure the level that allows for read times of up to 5.1 seconds in 20 millisecond intervals.
Helium recovered gas monitors:
GASMAN is a device used to measure the volume of helium gas
returned
to the liquefier equipment. A single unit was started on April 12, 1996
to monitor the gas flow from 24 different gas meters in Williamson
Hall.
This was the most prudent method to retrofit Williamson's gas recovery
monitoring system. Wiring was already in place to a central location
where
the GASMAN device was logically installed. In new systems such as the
New
Physics Building, individual GASMEN are installed at each lab's gas
meter
and rely on the single loop cable of the CRYONET instead of multiwire
star
wiring.
| GASMAN | Lab Room # | Lab Name |
| 1 | B102 | Cryogenics Master |
| 2 | B125 | Cryogenics Liquefier |
| 3 | B123 | Cryogenics Dewar Storage |
| 4 | B134 | Sullivan Blue |
| 5 | B134 | Sullivan White |
| 6 | B134 | Sullivan |
| 7 | B134 | Sullivan A |
| 8 | B138 | Sullivan |
| 9 | B124 | Ihas |
| 10 | B126 | Saab |
| 11 | B130 | Takano |
| 12 | B39 | SHIVA |
| 13 | B25 | Chan |
| 14 | B153 | Takano |
| 15 | B155 | Unused in NanoTech |
| 16 | B135 | Meisel |
| 17 | B137 | Lee |
| 18 | B131 | Lee |
| 19 | B38 | Hebard II |
| 20 | B48 | Stewart/Andraka |
| 21 | B158 | Hill |
| 22 | 1111 | Petkova |
| 23 | 1126 | Tanner |
| 25 | B104A | Cryogenics UFBI |
| 26 | B104A | Cryogenics Williamson |
| 27 | B122 | Bowers |
| 28 | B125D | Dewar Storage |
| 29 | B32 | Biswas |
| 30 | B20 | User Lab |
| 31 |
B158 |
Hill LN2 Small Red
Cryostat
(Temporary) |
| 32 |
1111 |
Petkova LN2 testing
NMR Magnet
(Temporary) |
| 33 |
B158 |
Hill Small Red
Cryostat |
| 34 |
1126B |
Tanner Flow cryostat |
The Dream: Cryostat monitoring along with
Pressure and
Temperature
monitors would complete the system for allowing full remote monitoring
and inventorying.
Realized:
Added the Omeganet to monitor Temperatures and Pressures and RS-232
connected most other level meters for complete monitoring.
The CRASH: (old news) MONDAY 3-18-96. On
Thursday 3-14-96
between
14:00 and 14:30 there was our first major crash of the CRYONET.
Apparently
after a transfer was completed in MicroKelvin and Dewar 9 was
reconnected
to the CRYONET a crash occurred. At this time it is not know if HLD 9
being
connected was the trigger for the crash or not. Only Dewar 4 was not
connected
to the CRYONET and it did not crash. Also, GAS 1 was connected and it
did
not crash. HLD 2,3,4,9 & 16 were reset and recalibrated using
the
old
data from the last calibration and they appear to have worked fine
since
Thursday. HLD 1 was hot and was not put it back in service until Monday
morning. Suspicion is that the fiber optic link was somehow a part of
the
problem. Maybe connecting HLD 9 caused the optic link to oscillate and
the oscillations locked up all connected HLD’s. Since GAS 1 uses
different
code it was not affected in the same way. The problem was attacked in
the
following way.
1. Look at the HLD code for something have missed.
2. Turn one of the test HC711 boards in to a CRYONET monitor.
3. Look at using the COP interrupt to catch runaway code and soft
restart
the HLD.
4. Examine the fiber optic link for unseen problems.
The CRASH II: Friday 3-3-00. During the
normal inventory
procedures
almost no cryonet devices responded. Record checking indicated that
between
17:00 and 18:00 on 3-2-00 the cryonet stopped working. By disconnecting
most HLDs the Cryonet recovered. Then one by one the HLDs were plugged
back in, testing the cryonet each time. A shorted 9-pin connector was
found
in the Cryogenics area. It was one of the most heavily used connectors
in the system. A dewar was plugged in at that location at ~17:30. The
connector
has been replaced.
Major upgrade 04-21-2000
On 4-21-2000 the microprocessors were replaced in all 16 HLDs. They are all running new code. The commux also upgraded to new code and microprocessors.
The Crash III: Wednesday 02-13-2002, A
short to ground in the
probe of HLD 9 took down the network.
Major Addition
2006: Added
the "Omeganet" to monitor the temperature and pressures of the helium
banks and the nitrogen gas distribution system.