Troubleshooting the ALS Control System
Description of the ALS Beamline Equipment Protection System (EPS)
Some basic ALS Documentation for EPS and RSS
- LSBL-151 ALS Beamline Control System Architecture
- LSBL-152 ALS Beamline Radiation Safety System: Design Requirements
- LSBL-153 ALS Beamline Equipment Protection System: Design Requirements
- LSBL-157 ALS Beamline Equipment Protection System: Front-end Controller
What is EPS?
EPS is an acronym for Equipment Protection System. The Beamline EPS at
ALS is a system of hardware and software components used to:
- protect the Storage Ring Vacuum from contamination
- protect beamline components from thermal damage
- provide operator control of beamline valves and shutters
What is RSS?
RSS is an acronym for Radiation Safety System. The Beamline RSS at ALS
consists of an interlock system which is used to:
- open or close the Personnel Safety Shutters and/or
- inhibit the Storage Ring from storing beam
whenever radiation safety is compromised in the beamline area.
The EPS signals the RSS to open or close the Personnel Safety Shutter
as requestedby the beamline operator.
Typical Beamline EPS Components
Remote Operated Vacuum Valves (VVR)
Vacuum valves are used to isolate sections of the beamline vacuum.
They are typically pneumatically actuated. Open and closed position
sensors are provided. Valves must be protected from the thermal
energy of the beam when closed.
Photon Shutters (PS)
Photon shutters are used to block the passage of light through the
beamline. They may be pneumatically or solenoid actuated. Open and
closed position sensors are provided. Photon shutters are usually
cooled by a flow of water to remove the beam energy.
Fast Acting Valves (FV)
Fast valves provide a fast (~20mSEC) closure in case of sudden loss of
vacuum in the branchline. They are pneumatically opened but closed
by spring pressure.
The fast valve is controlled by a VAT Fast Valve Control System.
Closing is triggered by Fast Sensors (FS) located in the branchlines.
Opening is requested by the beamline operator via the EPS panel.
When closed, the fast valve must be protected from thermal energy of the
beam by closing the photon shutter or by turning off the storage ring
electron beam.
Personnel Safety Shutter (PSS)
The PSS is used to prevent the emission of harmful radiation through
the storage ring shielding.
The PSS is controlled and monitored by the Radiation Safety System.
Coolant flow to the PSS is monitored by the EPS and interlocked to
the operation of the photon shutter.
Vacuum Ion Gauges (IG)
Ion Gauges are used to measure beamline pressures. The associated
Ion Gauge Controller provides a signal to the EPS indicating when
the monitored pressure is proper. Improper (high) pressure usually
requires the EPS to close valves upstream and downstream of the gauge.
Water Flow Switches (WFS)
Flow switches are used to detect a loss of coolant flow to beamline
components. Loss of coolant usually requires closing a photon
shutter or turning off the storage ring.
Programmable Logic Controller (PLC)
A PLC is a small microprocessor-based controller. It processes inputs
from sensors on the beamline components and from operator inputs to derive
outputs which control the beamline valves and shutters.
A program, referred to as ladder logic, is stored in the PLC's non-volatile
memory. While the PLC is running, it continuously scans the inputs, solves
the logic, and drives the outputs.
Modicon 984-A145 PLCs are used in the ALS Beamline EPS. These PLCs are
mounted on a backplane system which also mounts various types of Modicon
Input and Output modules.
Modicon PLCs may be interconnected by the Modbus or Modbus Plus network
allowing them to exchange data. Modbus Plus is a two-wire multi-drop
Token-Ring network. Modbus is an RS-232 based connection used to connect
a PLC to a Control Panel or computer.
Two PLCs are used for each ALS Sector Beamline/Branchline Front End EPS.
The BLFE PLC, located at the Sector Storage Ring Racks, controls beamline
valves located inside the Storage Ring shielding and interfaces to the
Storage Ring EPS and Instrument Control System. The BRFE PLC, located at
the Sector Facility Racks, controls branchline valves and the Personnel
Safety Shutter. The BLFE and BRFE exchange status information via a
ModBus Plus network.
Modicon input and output modules used in the EPS:
DEP216
16 channel 24 V digital input module. Used for monitoring interlocks,
valve positions, external permits, etc.
DAP216
16 channel 24 V digital output module. Used to actuate valves and
shutters and signal other systems.
DAP220
8 isolated 24v digital inputs, 8 isolated 24V digital outputs. Used to
interconnect to other EPS PLCs which must be isolated from the local
24 Volt Power Supply, i.e., between the Branchline Front End EPS and
the Branchline EPS.
ADU205
4 channel analog input module. Used to monitor Beamline Front End
Ion Gauge pressures. Converts -10V to +10V input to a 12 bit value
plus sign.
Operator Control Panel (PanelMate)
The Beamline Operator Panel (BLOP), located at the sector facilities rack,
provides a visual indication of the beamline/branchline status. Keypads
on the panel allow an operator to manipulate the beamline components.
Symbols on the panel can be configured to change color, shape, or label in
response to values read from the PLCs. Alarm conditions can be detected
and logged to an alarm page.
Troubleshooting the ALS Beamline Equipment Protection System
It is important to remember that most fault conditions in the EPS will be
due to real failures in the beamline components, i.e., water flow, vacuum,
valve sensors, etc. and not due to PLC modules or programming. These faults
will be annunciated on the PanelMate in enough detail to determine the
problem.
For faults which are not so apparent, the front panel indicators of the
PLC and I/O modules should be examined.
PLC CPU
- Ready and Run lights should be on. (Wait 20 Secs after power-on.)
- ModBus light may be on if cable plugged into Modbus connector.
- MB Plus light should blink at 6 Hz if cable plugged into MBplus connector.
DAP216 Output Module
- Green LEDs opposite screws 1 and 12 indicate 24 V from power supply.
(Check switch and fuse in 24 V distribution panel.)
- Amber LEDs opposite screws 2 and 13 indicate output overload or short.
(Try yellow Reset button located at top front of module.)
- Red LEDs opposite screws 3...10 and 14...21 are ON if channel is ON.
(Chart on front of module cover identifies device for each channel.)
DEP216 Input Module
- Green LEDs opposite screws 1 and 12 indicate 24 V from power supply.
(Check switch and fuse in 24 V distribution panel.)
- Red LEDs opposite screws 3...10 and 14...21 are ON if channel is ON.
(Chart on front of module cover identifies device for each channel.)
DAP220 Combined Input/Output Module
- Green LED opposite screw 1 indicates 24 V is available for outputs.
(This 24 V is supplied from the branchline EPS.)
- Green LED opposite screw 12 indicates 24 V is available for inputs.
(This 24 V is supplied from the branchline EPS.)
- Red LEDs opposite screws 3...10 ON if channel output is ON.
(Chart on front of module cover identifies device for each channel.)
- Red LEDs opposite screws 14...21 are ON if channel input is ON.
(Chart on front of module cover identifies device for each channel.)
- replacing modules
- reprogramming PLCs
- development tools
- sources (cvs /home/als2)
-
- Assistance:
- Ken Woolfe - EPS general questions, PLC hardware & software, Fast Valve Controls, System wiring
- Hanjing Huang - PLC programming, Labview EPS display
- Beamline Coordinators (John Pruyn, Donna Hammamoto) - System operation and trouble-shooting
- Frank Zucca - Vacuum systems, Valves, Shutters
- Craig Hopkins - Water Flow Switches
- Bob Mueller - RSS and PSS interlocks
- Carl Cork - Original architect and designer of ALS Beamline EPS
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