MKS 946 Series User manual

Series 946 Vacuum System Controller
Operation and Maintenance Manual
Instruction Manual p/n: 100018121
Rev A, June 2020

946 Controller Instruction Manual pg. 2
Table of Contents
1Safety Information ......................................................................................... 6
1.1 Symbols Used in this Manual and their definitions ............................................... 6
1.2 Safety Precautions ............................................................................................... 6
1.2.1 Safety Procedures and Precautions ............................................................................................. 6
2Specifications ................................................................................................ 8
2.1 Controller ............................................................................................................. 8
2.2 Pressure, Flow Sensors, & Valves ..................................................................... 10
2.3 Controller Display .............................................................................................. 14
2.3.1 Display Message ........................................................................................................................ 14
2.3.2 Display Resolutions .................................................................................................................... 15
2.3.3 Serial Communication Response Format ................................................................................... 16
3Feature, Control Locations and Dimensions ............................................ 17
4Typical Applications for the Series 946 Controller ................................... 19
5MKS Series 946 Vacuum System Controller ............................................. 20
6Operating the Series 946 Controller .......................................................... 22
6.1 Power ................................................................................................................ 22
6.2 Front Panel Control Lock ................................................................................... 22
6.3 Front Panel Display ........................................................................................... 22
6.3.1 Standard Front Panel Display .................................................................................................... 22
6.3.2 Large Font Display ..................................................................................................................... 24
6.4 System Setup .................................................................................................... 24
6.4.1 Overview of 946 System Setup .................................................................................................. 24
6.4.2 Display System Setup Parameters ............................................................................................. 25
6.4.3 Change and Save a Parameter Value ........................................................................................ 26
6.4.4 Description of the System Setup Parameters ............................................................................. 26
6.5 Channel Setup for Pressure Measurement ........................................................ 30
6.5.1 Overview of 946 Channel Setup ................................................................................................. 30
6.5.2 Setup for a Capacitance Manometer .......................................................................................... 32
6.5.3 Setup for a CP (Convection Pirani), Convectron, or PR Sensor ................................................. 35
6.5.4 Setup a Cold Cathode Sensor .................................................................................................... 38
6.5.5 Setup a Hot Cathode Sensor ..................................................................................................... 41
6.6 Power Control of a Pressure Sensor .................................................................. 45
6.6.1 Power (including degas) Control of a Sensor using Front Panel Control Button ........................ 45
6.6.2 Power (including degas) Control of a Sensor via 37 pin AIO D-sub Connector .......................... 46
6.6.3 Power (including degas) Control of a Sensor using Serial Communication Commands ............ 46
6.7 Channel Setup for Flow Measurement and MFC Based Pressure Control ......... 47
6.7.1 Simple Operation of a Mass Flow Controller .............................................................................. 47
6.7.2 Setup MFC Controlling Parameters for Flow Control ................................................................. 48
6.7.3 Set MFC(s) for Dynamically Controlling System Pressure ......................................................... 50
6.8 Pressure Control using a Control Valve ............................................................. 60
6.8.1 Valve Type Selection .................................................................................................................. 61
6.8.2 Valve Control Recipe Setup ....................................................................................................... 62
6.8.3 Activate a Pressure Control with a Valve ................................................................................... 63
6.8.4 Terminate a PID Pressure Control using a Valve ....................................................................... 64
7Installing Vacuum Sensors ......................................................................... 66
7.1 Installing Cold Cathode Sensors ........................................................................ 66
7.1.1 Locating a Cold Cathode Sensor................................................................................................ 66
7.1.2 Orienting a Cold Cathode Sensor............................................................................................... 66
7.1.3 Managing Contamination in a Cold Cathode Sensor.................................................................. 66
7.1.4 Connecting the Series 431/422 Sensor ...................................................................................... 66
7.1.5 Connecting the 423 I-Mag Sensor .............................................................................................. 67

946 Controller Instruction Manual pg. 3
7.2 Installing Hot Cathode Sensors.......................................................................... 67
7.2.1 Over Pressure Conditions .......................................................................................................... 67
7.2.2 Locating a Hot Cathode Sensor ................................................................................................. 67
7.2.3 Preventing Contamination in a Hot Cathode Sensor .................................................................. 67
7.2.4 Orienting a Hot Cathode Sensor ................................................................................................ 68
7.2.5 Connecting a Hot Cathode Sensor to the Vacuum System ........................................................ 68
7.2.6 Connecting a Hot Cathode Sensor to the 946 Controller ........................................................... 68
7.3 Installing Convection Pirani, Convectron, or Pirani Sensors ............................... 69
7.3.1 Over Pressure Conditions .......................................................................................................... 69
7.3.2 Locating the Sensor ................................................................................................................... 70
7.3.3 Preventing Contamination in a Pirani Sensor ............................................................................. 70
7.3.4 Orienting the Series 317Convection Pirani or Convectron Sensor ............................................. 70
7.3.5 Orienting the Series 345 Pirani Sensor ...................................................................................... 70
7.3.6 Connecting Convection Pirani, Convectron, or Pirani Sensors .................................................. 70
7.3.7 Preparing the 317 Sensor for Bakeout ....................................................................................... 71
7.4 Installing Capacitance Manometers - MKS Baratron .......................................... 72
7.4.1 Installing a Capacitance Manometer .......................................................................................... 72
7.4.2 Connecting a Capacitance Manometer ...................................................................................... 72
7.5 Series 902B Piezo ............................................................................................. 73
7.6 Installing Mass Flow Controllers ........................................................................ 73
7.6.1 Environmental requirements ...................................................................................................... 73
7.6.2 Interface Cables ......................................................................................................................... 73
7.6.3 Setup .......................................................................................................................................... 74
7.6.4 Gas Line Connections ................................................................................................................ 74
7.7 Installing a Pressure Control Valve .................................................................... 74
7.7.1 Installing an Upstream Solenoid Valve ....................................................................................... 74
7.7.2 Installing a Downstream MKS 153 or T3B Throttle Valve ........................................................... 75
8Connecting Relay and Analog Outputs ..................................................... 77
8.1 Connecting 946 Relay Outputs ...................................................................................... 77
8.1.1 Pin Out for the 946 Relay Output ............................................................................................... 77
8.1.2 Proper Setting of a Relay ........................................................................................................... 78
8.1.3 Relay Inductive Loads and Arc Suppression .............................................................................. 79
8.2 Connecting the 946 Analog Output .................................................................... 79
8.3 Buffered Analog Output ..................................................................................... 80
8.4 Logarithmic/Linear and Combination Analog Output .......................................... 91
8.4.1 Logarithmic/Linear Analog Output .............................................................................................. 91
8.4.2 Combination Analog Output ....................................................................................................... 91
8.4.3 Logarithmic/Linear Analog Output when the Sensor Power is Turned OFF ............................... 93
9RS232/485 Serial Communication Commands ......................................... 94
9.1 Serial Communication Wiring Diagram .............................................................. 94
9.2 Communication Protocols .................................................................................. 94
9.3 Pressure Reading Commands ........................................................................... 95
9.4 Relay and Control Setting Commands ............................................................... 96
9.5 Capacitance Manometer Control Commands .................................................... 97
9.6 Convection Pirani, Convectron and Pirani Control Commands .......................... 97
9.7 Cold Cathode Control Commands ..................................................................... 98
9.8 Hot Cathode Control Commands ....................................................................... 99
9.9 MFC Control Commands ................................................................................. 100
9.10 Pressure (Valve) Control Commands............................................................... 100
9.11 PID Recipe Setting Commands ....................................................................... 101
9.12 Ratio Recipe Setting Commands ..................................................................... 102
9.13 PID/Ratio Control Activation Command ........................................................... 102

946 Controller Instruction Manual pg. 4
9.14 System Commands ......................................................................................... 103
9.15 Error Codes ..................................................................................................... 105
10 Maintenance of Series 946 Controller Modules ...................................... 106
10.1 Removing and Installing a Sensor Module ....................................................... 106
10.2 Removing and Installing AIO Module ............................................................... 107
10.3 Pressure Control (PC) Module ......................................................................... 108
10.4 Mounting the 946 Controller ............................................................................. 109
10.5 AC Power Cord ................................................................................................ 110
11 Maintenance and Service of MKS Vacuum Sensors .............................. 111
11.1 422 and 431 Cold Cathode Sensor .................................................................. 111
11.1.1 Cold Cathode Theory ............................................................................................................... 111
11.1.2 Maintenance of Series 431/422 Cold Cathode Sensor............................................................. 112
11.2 Maintenance of Series 423 I-Mag Cold Cathode Sensor.................................. 115
11.2.1 Disassemble the I-Mag Sensor ................................................................................................ 115
11.2.2 Clean the I-Mag Sensor ........................................................................................................... 117
11.2.3 Assemble the I-Mag Sensor ..................................................................................................... 117
11.2.4 Preparing the Sensor for Bakeout ............................................................................................ 118
11.3 Maintenance of Low Power Nude and Mini BA Hot Cathode Sensors.............. 118
11.3.1 Hot Cathode Theory ................................................................................................................. 118
11.3.2 Cleaning the Hot Cathode Sensor ............................................................................................ 119
11.3.3 Testing the Hot Cathode Sensor .............................................................................................. 119
11.4 Maintenance of a Pirani Sensor ....................................................................... 120
11.4.1 Theory of a Pirani Pressure Sensor ......................................................................................... 120
11.4.2 Cleaning the Series 345 Sensor ............................................................................................... 121
11.4.3 Cleaning the Series 317 Sensor ............................................................................................... 122
11.5 Maintenance of a Capacitance Manometer ...................................................... 123
11.5.1 Theory of a Capacitance Manometer ....................................................................................... 123
11.5.2 Repairing the Baratron Capacitance Manometer ..................................................................... 124
12 Spare Parts and Accessories ................................................................... 125
13 Appendix .................................................................................................... 127
13.1 MFC Gas Conversion Factors for Selected Gases .................................................... 127

946 Controller Instruction Manual pg. 5
Package Contents
Before unpacking the 946 Controller, check all surfaces of the packing material for shipping
damage. Check to be sure that the 946 system contains the following items:
• 1 Series 946 Controller (with selected modules installed)
• 1 female, 25-pin D-sub connector for relay output connection
• 1 male, 37pin D-sub connector for analog output connection
• 1 10-foot power cord (US customer only)
Service and Warranty Guidelines
Some minor problems are readily corrected on site. If the product requires service, contact the MKS
Technical Support Department at [phone]. If the product must be returned to the factory for
service, request a Return Material Authorization (RMA) from MKS. Do not return products without first
obtaining an RMA. In some cases a hazardous materials disclosure form may be required. The MKS
Customer Service Representative will advise you if the hazardous materials document is required.
When returning products to MKS, be sure to package the products to prevent shipping damage. Shipping
damage on returned products due to inadequate packaging is the Buyer's responsibility.
For Customer Service / Technical Support:
MKS Global Headquarters
2 Tech Drive, Suite 201
Andover MA, 01810 USA
Phone: [phone]
Email: [e-mail]
Visit our website at: www.mksinst.com
Warranty Information
MKS Instruments, Inc. provides an eighteen (18) month warranty from the date of shipment for new MKS
products. The MKS Instruments, Inc. general terms and conditions of sale provide the complete and
exclusive warranty for MKS products. This document is located on our web site at www.mksinst.com, or
may be obtained by a contacting an MKS customer service representative.
© 2020, MKS Instruments, Inc. All rights reserved. Granville-Phillips®, Baratron®, Convectron®, and I-Mag® are
registered trademarks, and mksinstTM is a trademark of MKS Instruments, Inc. All other trademarks and registered
trademarks are the properties of their respective owners.

946 Controller Instruction Manual pg. 6
1 Safety Information
1.1 Symbols Used in this Manual and their definitions
CAUTION: Risk of electrical shock.
CAUTION: Refer to manual. Failure to read message could result
in personal injury or serious damage to the equipment or both.
CAUTION: Hot surface.
Calls attention to important procedure, practice, or conditions.
Failure to read message could result in damage to the equipment.
1.2 Safety Precautions
1.2.1 Safety Procedures and Precautions
The following general safety precautions must be observed during all phases of operation of this
instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual
violates safety standards for the intended use of the instrument and may impair the protection provided by
the equipment. MKS Instruments, Inc. assumes no liability for the customer’s failure to comply with these
requirements.
Properly Ground the Controller.
This product is grounded through the grounding conductor of the power cord. To avoid electrical shock,
plug the power cord into a properly wired receptacle before connecting it to the product input terminals. A
protective ground connection through the grounding conductor in the power cord is essential for safe
operation.
Upon loss of the protective-ground connection, all accessible conductive parts (including knobs and
controls that may appear to be insulating) can render an electrical shock.
All components of a vacuum system used with this or any similar high voltage product must be
maintained at Earth ground for safe operation. Be aware, however, that grounding this product does
not guarantee that other components of the vacuum system are maintained at earth ground. Connecting
the power cable only to a properly grounded outlet is necessary but not sufficient for safe operation of a
vacuum system with this or any similar high voltage producing product. Verify that the vacuum port to
which the sensors are mounted is electrically grounded.

946 Controller Instruction Manual pg. 7
Some of the sensors operated by the 946 Controller are highly gas sensitive and were calibrated
with a specific gas. When used with other gases, the true pressure could be much higher than the
indicated pressure. Read and understand the information provided in this manual about setting up,
installing and operating each sensor type with different gases.
Do not substitute parts or modify the instrument.
Do not install substitute parts or perform any unauthorized modification to the instrument. Return the
instrument to an MKS Calibration and Service Center for service and repair to ensure that all safety
features are maintained.
Use proper electrical fittings.
Dangerous voltages are contained within this instrument. All electrical fittings and cables must be of the
type specified, and in good condition. All electrical fittings must be properly connected and grounded.
The Series 946 Controller contains lethal voltages when on.
High voltage is present in the cable and a Cold Cathode sensor when the Controller is turned on.
Use the proper power source.
This product is intended to operate from a power source that applies a voltage between the supply
conductors, or between either of the supply conductors and ground, not more than that specified in the
manual.
Use the proper fuse.
Only use a fuse of the type, voltage rating, and current rating specified for your product.
Do not operate in explosive environment.
To avoid explosion, do not operate this product in an explosive environment unless it has been specially
certified for such operation.
Service by qualified personnel only.
Operating personnel must not remove instrument covers. Component replacement and internal
adjustments must only be made by qualified service personnel.
Use proper power cord.
Only use a power cord that is in good condition and that meets the input power requirements specified in
the manual.
Only use a detachable cord set with conductors having a cross-sectional area equal to or greater than
0.75 mm2. The power cable should be approved by a qualified agency such as VDE, Semko, or SEV.

946 Controller Instruction Manual pg. 8
2 Specifications1
2.1 Controller
Pressure measuring range2 1 x 10-11 to 1.0 x 10+4 Torr
1 x 10-11 to 1.3 x 10+4 mbar
1 x 10-9 to 1.3 x 10+6 Pa
Relay set point range3
CC (Cold Cathode) 2.0 x 10-10 to 5.0 x 10-3 Torr
2.7 x 10-10 to 6.5 x 10-3 mbar
2.7 x 10-8 to 6.5 x 10-1 Pa
HC (Hot Cathode) 5.0 x 10-10 to 5.0 x 10-3 Torr
6.5 x 10-10 to 6.5 x 10-3 mbar
6.5 x 10-8 to 6.5 x 10-1 Pa
Pirani 2.0 x 10-3 to 9.5 x 10+1 Torr
2.7 x 10-3 to 1.2 x 10+2 mbar
2.7 x 10-1 to 1.2 x 10+4 Pa
CP (Convection Pirani) 2.0 x 10-3 to 9.5 x 10+2 Torr
2.7 x 10-3 to 1.2 x 10+3 mbar
2.7 x 10-1 to 1.2 x 10+5 Pa
CM (Absolute Manometer) 0.2% to 100% of the measurement range of the head (e.g. 1 Torr
head is 2.0 x 10-3 to 1.0 x 10+0 Torr)
FC (Mass Flow Controller) 0.2% to 100% of the measurement range of the MFC (e.g. 1000
SCCM MFC is 2.0 x 10+0 to 1.0 x 10+3 SCCM)
Allowed range within which a control sensor may switch on a Cold or Hot Cathode
Pirani 5.0 x 10-4 to 9.5 x 10-1 Torr
6.5 x 10-4 to 1.3 x 10-1 mbar
6.5 x 10-2 to 1.3 x 101 Pa
CP (Convection Pirani) 2.0 x 10-3 to 1.0 x 10-2 Torr
2.7 x 10-3 to 1.3 x 10-1 mbar
2.7 x 10-1 to 1.3 x 101 Pa
CM (≤2T head) 1.0 x 10-1 to 0.2% of FS Torr
1.3 x 10-1 to 0.2% of FS mbar
1.3 x 10+1 to 0.2% of FS Pa
Protection set point4
CC & HC 1.0x10-5 to 1.0x10-2 Torr, default setting: 5.0x10-3 Torr
Operating temperature range 5° to 40°C (41° to 104°F)
1 Specifications subject to change without notice.
2 The measurement range depends upon the sensor options selected.
3 Relay set point values are automatically adjusted when pressure unit is changed.
4 The protection set point is always enabled in 946.

946 Controller Instruction Manual pg. 9
Storage temperature range -10° to 55°C (14° to 131°F)
Relative humidity 80% maximum for temperatures less than 31°C, decreasing
linearly to 50% maximum at 40°C
Altitude 2000 m (6561 ft) maximum
Insulation coordination Installation (Over-voltage) Category II, Pollution Degree 2
Power requirement (nominal) 100 - 240 VAC, 50/60 Hz
Mains voltage Fluctuations not to exceed ±10% of nominal
Power consumption 150 W maximum
Fuse rating, size 2X2A, 250V, Ø 5 mm x 20 mm
Process control relay 12 nonvolatile relays, (4 for each sensor module)
Relay rating SPDT, 2 A @ 30 V resistive
Relay response 150 msec maximum
Analog outputs5 One Buffered and one Logarithmic ( Linear
( ) for each channel, up to two (2) wide-range
combination logarithmic outputs. Output impedance = 100 ohms
Number of channels Up to 6
Front panel controls Power ON-OFF switch, keypad for setup and operational
commands.
Display 320x240 color LCD with back lighting.
Pressure units Torr, mbar, Pascal or microns
Flow units SCCM (≤10,000 SCCM) and slm (>10 slm)
Update rate LCD display is updated 3 times per second. The pressure/flow
signals are updated every 50 msec.
Sensor module slots 3
Sensor modules channels/module
Cold Cathode single
Hot Cathode single
Pirani/Convection Pirani dual
Capacitance Manometer dual
MFC dual
COMM/Control modules
Pressure Control
Computer interface Serial – RS-232 and RS-485; 9600, 19200, 38400, 57600,115200
baud rate selectable
Electronic casing Aluminum
5 Logarithmic/linear and combined logarithmic analog outputs can be customized using the system setup
menu.

946 Controller Instruction Manual pg. 10
Dimensions (W x D x H) 9½" x 12¼" x 3½" (241 mm x 311 mm x 88 mm)
Size ½ rack, 2U high
Typical weight 8.0 lb (3.6 kg)
CE certification EMC Directive: 2004/108/EEC
Low Voltage Directive: 73/23/EEC
2.2 Pressure, Flow Sensors, & Valves
Sensor type
CC (Cold Cathode) Series 431 and 422 inverted magnetron
Series 423 I-Mag
HC (Hot Cathode) Bayard-Alpert (BA) type ionization sensors including MKS MIG
(Miniature Ionization Gauge), or LPN (Low Power Nude)
Pirani Series 345 Pirani
CP (Convection Pirani) Series 317 Convection Pirani
Series 275 Convectron®
CM (Capacitance Manometer) MKS unheated Baratron® or MKS 45 C heated Baratron, with
suitable cable connections and full-scale ranges. Each CM
module operates up to two Capacitance Manometers, and the
total current requirement of operating sensor(s) must be 1 amp
or less.
FC (Mass Flow Controller) MKS G, I, P Series and legacy products with tied internal
grounds, MFCs requiring ±15 VDC or +15 to +24 VDC, 0 - 5
VDC set point and standard 15 pin or 9 pin D-sub cable
connection
Valve Pressure Control Valves: MKS 248A, 148J, 154A (Solenoid
Control Valve), 153D and T3Bi (Exhaust Throttle Valves)
Pressure & Flow measurement ranges
CC (Cold Cathode) 1.0 x 10-11 to 1.0 x 10-2 Torr
1.3 x 10-11 to 1.3 x 10-2 mbar
1.3 x 10-9 to 1.3 x 10+0 Pa
HC (Hot Cathode) 1 .0x 10-10 to 1.0 x 10-2 Torr
1.3 x 10-10 to 1.3 x 10-2 mbar
1.3 x 10-8 to 1.3 x 10+0 Pa
Pirani 5.0 x 10-4 to 4.0 x 10+2 Torr
6.5 x 10-4 to 5.2 x 10+2 mbar
6.5 x 10-2 to 5.2 x 10+4 Pa
CP (Convection Pirani) 1.0 x 10-3 to 1.0 x 10+3 Torr
1.3 x 10-3 to 1.3 x 10+3 mbar
1.3 x 10-1 to 1.3 x 10+5 Pa
CM (Capacitance Manometer) Three decades below full scale of head, (e.g., 10 Torr head is
1.0 x 10-2 to 1.0 x 10+1 Torr)
Flow Range (MFC) 1 SCCM to 1,000 SLM

946 Controller Instruction Manual pg. 11
Response time (Buffered analog output)
CC <40 msec6
HC <50 msec
Pirani, CP <80 msec
CM <40 msec
Response time (Log/Lin analog output)
CC <50 msec
HC <50 msec
Pirani, CP <80 msec
CM <80 msec
Resolution7
CC 2 significant digits between 10-10 and 10-2 Torr, 1 significant digit
in 10-11 Torr decade
HC 2 significant digits between 10-9 and 10-2 Torr; 1 significant digit
in 10-10 Torr decade
Pirani 1 significant digit from 450 to 100 Torr; 2 significant digits
between 10-4 and 100 Torr
CP, Convectron 2 significant digits over the entire range.
CM & FC 4 significant digits from 10 to 100% FS, 3 significant digits from 1
to 10% FS, 2 significant digits from 0.1 to 1% FS, 1 significant
digit from 0.01 to 0.1% FS.
Repeatability
CC, HC, Pirani, CP 5% of indicated pressure at constant temperature
CM 0.25% of indicated pressure at constant temperature
FC 0.2% of full scale
Calibration gas
CC, HC Nitrogen, Argon
Pirani, CP Air/nitrogen, Argon, Helium
CM Any (gas independent)
FC Nitrogen
6A fast response (<3 msec) Cold Cathode board is also available. Consult MKS for details.
7 Trailing zeros displayed on LCD screen do not reflect the resolution of the pressure reading.

946 Controller Instruction Manual pg. 12
Installation orientation
CC, HC, CM, Pirani, FC Any (port down suggested for pressure sensor)
CP Body horizontal only
Materials exposed to vacuum may include
CC Series 431 and 422 – SS 304, Al 6061, silver-copper brazing
alloy, alumina ceramic, Elgiloy®, OFHC® copper
Series 423– SS 302, SS 304, glass, Al, Inconel X-750®, alumina
ceramic
HC 304 SS, Inconel® X750, glass, tungsten, platinum clad
molybdenum, tantalum, nickel, braze alloy, either yttria coated
iridium or tungsten filament
Pirani 300 series stainless, platinum, glass, alumina ceramic, silver
brazing alloy, nickel 200
CP 300 series stainless, nickel, glass, platinum
Convectron 304 stainless steel, borosilicate glass, Kovar®, Alumina,
NiFe alloy, polyimide
CM Inconel®
FC 316 series stainless, nickel, Elgiloy®, elastomer seal.
Internal volume8
CC Series 431 and 422 - 1.8 in3 (30 cm3)
Series 423 - 0.9 in3 (15 cm3)
HC Low power nude tube - zero
Mini BA - 1.4 in3 (23 cm3)
Pirani 0.5 in3 (8 cm3)
CP 2.0 in3 (33 cm3)
Convectron 304 stainless steel, borosilicate glass, Kovar®, Alumina,
NiFe alloy, polyimide
CM Type 622A/623A/626A - 0.38 in.3 (6.3 cm3)
Type 722A -0.3 in.3 (4.9 cm3)
FC 0.27 in3 (4.43 cm3)
Operating temperature range
CC Series 431 - 0° to 70°C (32° to 158°F)
Series 422--Versions available that operate up to 250°C.
Series 423 - 0° to 70°C (32° to 158°F)
Pirani & HC 0° to 50°C (32° to 122°F)
8 Volume will vary with the type of vacuum connection selected

946 Controller Instruction Manual pg. 13
CP 10° to 50°C (50° to 122°F)
CM & FC 0° to 50°C (32° to 122°F)
Maximum Sensor bakeout temperature (without cables)
CC Series 431 – 250°C (482°F) when backshell subassembly
removed, 125°C (257°F) otherwise
Series 423 – 400°C (752°F) CF flange version only with magnet
removed
Series 422-versions bakable and operable to 250°C are
available.
HC 60oC (104°F) with cable attached
300oC (572°F) max, with CF, cable removed 150oC
(302°F), with KF and Viton® seal, cable removed
Pirani 50°C (122°F)
CP 100°C (212°F) plastic shell internally coated for RF shielding
250°C (482°F) on aluminum housing for RF shielding version.
Convectron 150°C (302°F)
CM & FC N/A
Hot cathode sensitivity
LPN 9 Torr-1 (20%)
Mini BA 12 Torr-1 (20%)
Hot Cathode filament type
LPN Tungsten (W) or Yttria (Y2O3) coated iridium
Mini BA Yttria (Y2O3) coated iridium
Hot Cathode degas power (E-beam, at grid)
LPN 20 W max
Mini BA 5 W max
Operating voltages
HC Grid: 180 VDC (normal operation); up to 600 V during degas
Filament bias: 30 VDC
Filament: 1.8 VDC @ 2A
CC 4.0 kVDC
Hot Cathode X-ray limit
LPN & Mini BA 3x10-10 Torr
Dimensions
CC Series 431 and 422 – 2.26.3 in (56160 mm)
Series 423 – 2.63.4 in (6686 mm)

946 Controller Instruction Manual pg. 14
Mini BA 1.12X2.37 in (2860 mm) with 2-3/4” CF flange
LPN 3.3X1.0 in (83 mm25) with 2-3/4 CF flange, can insert into
NW40 tube.
Pirani 1.3X4.4 in (34112 mm)
CP 1.6X4.4 in (41112 mm)
CM Types 622A, 623A and 626A - 2.64.8 in. (66121 mm)
Type 722A- 1.53.9 in (3899 mm)
FC (HWL) 1179A -<5.5<1.53 in (<14.0<3.87.6 mm)
Typical Weight
CC (with 2-3/4” CF flange) Series 431 and 422 - 2.4 lb (1.1 kg)
Series423 - 1.8 lb (0.8 kg)
LPN 0.9 lb (0.40 kg) with CF flange
Mini BA 0.816 lb (0.36 kg) with CF flange
Pirani 0.5 lb (0.2 kg)
CP (w/ KF Flange) 0.5 lb (0.2 kg)
FC <1.9 lb (0.86 kg)
2.3 Controller Display
2.3.1 Display Message
X.X0Eee
Normal pressure for the Pirani, CP, CC, and HC
X.XXXEe
Normal pressure for the Baratron, flow rate for MFC
OVER
The pressure is over upper limit (for CC and HC when p > 1x10-2 Torr)
ATM
Atmospheric pressure for the Pirani sensor
>1.100Ee
CM pressure is over 10% of the full scale
LO<E-11
The CC pressure is below its lower limit, or no CC sensor is connected
LO<E-10
The HC pressure is below its lower limit
LO<E-04
The Pirani pressure is below its lower limit
LO<E-03
The CP pressure is below its lower limit
OFF
Power is OFF to HC/CC/CP/PR sensor.
WAIT
CC and HC startup delay
Low EMIS
The HC OFF due to low emission current
CTRL OFF
The HC or CC are turned OFF by the control channel
PROT OFF
The HC or CC are in a protected state

946 Controller Instruction Manual pg. 15
RP OFF
The sensor power is turned OFF remotely
REDETECT
Detecting the sensor type for PR/CP
_ _ _ _
No Pirani/CP/HC/MFC sensor is detected on the inserted Pirani/CP board
NOBOARD
No board is detected in the slot, display only last 5 secs
N2, AR, He
Gas type
U
User calibration
SPn
Activated relay channel (n=1 to 12)
_ _
A relay is enabled, but not activated.
Ctrl
The CC/HC is controlled by another gauge (PR/CP)
AZ
PR/CP/BR may be auto-zeroed by its control sensor
F1, F2
Active filament
DG
The HC is degassing
An, Bn, Cn
The channel where the control sensor is installed (n=1, 2)
2.3.2 Display Resolutions
Resolution of the pressure values displayed on a 946 Vacuum System Controller front panel varies with
the type of sensor connected, and range of measurement. In addition, three display formats are available:
Default, HighR9 (high resolution), and PatchZ (patch zero) and can be selected based on preference.
PatchZ
Default/HighR
Percentage of Full-Scale
Displayed Resolution
Displayed Resolution
>110% FS
>(110%*FS value)
>(110%*FS value)
110% to 10%
X.XXXE+X
X.XXXE+X
10% to 1%
X.XX0E+X
X.XXE+X
1% to 0.1%
X.X00E+X
X.XE+X
<0.1%
X.000E+X
XE+X
Table 2-1 Capacitance Manometer with Exponential Display Format
Table 2-1 shows the exponential display format for Capacitance Manometer. If a Capacitance Manometer
measurement range is between 104 and 10 (regardless of pressure unit), it is possible to toggle between
the decimal and exponential formats. To do this, select the desired CM channel with the up down keys
until the LED indicator on the front panel is opposite the channel and press the
Degas
On/off
button.
9 When HighR mode is selected, the controller displays extra digit for ion gauge pressure to assist the
monitoring of pressure changes.

946 Controller Instruction Manual pg. 16
Pressure
Range
Convection Pirani
Pirani
Hot Cathode
Cold Cathode
Torr
PatchZ
Default
HighR
PatchZ
Default
HighR
PatchZ
Default
HighR
PatchZ
Default
HighR
103
X.X0E+03
X.XE+03
ATM
ATM
102
X.X0E+02
X.XE+02
X.00E+02
(X=1,2,3,4)
X.XE+02
10
X.X0E+01
X.XE+01
X.X0E+01
X.XE+01
1
X.X0E+00
X.XE+00
X.X0E+00
X.XE+00
10-1
X.X0E-01
X.XE-01
X.X0E-01
X.XE-01
10-2
X.X0E-02
X.XE-02
X.X0E-02
X.XE-02
X.X0E-02
XE-02
X.XE-02
X.X0E-02
XE-02
X.XE-02
10-3
X.X0E-03
X.XE-03
X.X0E-03
X.XE-03
X.X0E-03
X.XE-03
X.XXE-03
X.X0E-03
X.XE-03
X.XXE-03
10-4
LO<E-03
LO<E-03
X.X0E-04
(X.X down
to 1.3)
X.XE-04
(>5.0E-
04)
X.X0E-04
X.XE-04
X.XXE-04
X.X0E-04
X.XE-04
X.XXE-04
10-5
LO<E-04
LO<E-04
X.X0E-05
X.XE-05
X.XXE-05
X.X0E-05
X.XE-05
X.XXE-05
10-6
X.X0E-06
X.XE-06
X.XXE-06
X.X0E-06
X.XE-06
X.XXE-06
10-7
X.X0E-07
X.XE-07
X.XXE-07
X.X0E-07
X.XE-07
X.XXE-07
10-8
X.X0E-08
X.XE-08
X.XXE-08
X.X0E-08
X.XE-08
X.XXE-08
10-9
X.X0E-09
X.XE-09
X.XE-09
X.X0E-09
X.XE-09
X.XXE-09
10-10
X.00E-10
XE-10
XE-10
X.X0E-10
X.XE-10
X.XE-10
10-11
X.00E-11
XE-11
XE-11
Table 2-2 946 Pressure Display Format for Indirect Gauges including CP, PR, CC and HC
Table 2-2 shows that display format for indirect gauge including Pirani, Convectional Pirani, Cold Cathode
and Hot Cathode sensors.
2.3.3 Serial Communication Response Format
CM and Piezo
Diff
Baratron
Pirani
Convection
Hot Cathode
Cold Cathode
X.XXXE+X
X.XXXE+X
X.XXE-XX
X.XXE-XX
X.XXE-XX
X.XXE-XX
-X.XXE+X
Table 2-3 946 Serial Communication Response Format
Table 2-3 shows the serial communication (RS232/485) response format. In order to keep the
communication response string length consistent, 0 will be added or patched to the end if needed.

946 Controller Instruction Manual pg. 17
3 Feature, Control Locations and Dimensions
Power
OFF ON
A1
A2
B1
B2
C1
C2
946 VACUUM SYSTEM CONTROLLER
ESC Enter
CP
AR
1.00E-10
1.00E-10
1.20E-03
3.50E-02
C2
Ctrl
F2
DG
C1
Ctrl
Torr
SP11
SP12
SP9
SP10
SP5
SP6
SP7
SP8
SP1
SP2
SP3
SP4
PR
N2
HC
N2
CC
N2
Remote
A1
AZ
B1
AZ
Channel
Setup
System
Setup
Pressure
Control
Degas
On/off
Sensor
On/Off
Close
Setpoint
Open
8.87(225)
9.47(241)
3.00(76)
1 2 3 4 5
Figure 3-1 946 Front Panel
Figure 3-2 946 Rear Panel Example

946 Controller Instruction Manual pg. 18
Figure 3-3 946 External Dimensions (inches)
1
Channel Label
2
LED, Indicating Active Channel
3
Liquid Crystal Display
4
Push Buttons for Menu Navigation
5
Power Switch
6
AIO Module
7
AC Power Inlet
8
RS232/485 Communication Port
9
Relay Output Port
10
Analog Output Port
11
Pressure Control Module
12
Capacitance Manometer Module
13
Mass Flow Control Module
14
Pirani Module

946 Controller Instruction Manual pg. 19
4 Typical Applications for the Series 946 Controller
• Wide pressure measurement range in vacuum chambers.
• Integrated vacuum process control with simultaneous flow, pressure, and valve control.
• Pressure control in vacuum systems and process sequencing using relay set points.
• Sensing abnormal pressure events and initiating and controlling appropriate security
measures using the relay set points.
• Controlling system pressure by using the analog output as the input to an automatic pressure
controller.
• Starting or stopping system processes using relay set points.
• Measuring backfill pressures.
• Controlling accelerator and light source vacuum systems.
• Displaying the flow rates from MFCs and providing an interface for MFC setup.
• Control of gas flow into vacuum/process chamber.
• Maintaining accurate system pressure by controlling an upstream solenoid valve.
• Maintaining accurate system pressure by controlling a downstream throttle valve.
• Maintaining accurate system pressure by regulating a single MFC flow rate (single MFC PID
control), or multiple MFC flow rates with fixed ratio (ratio control).
• Maintaining smooth control of a wide range of pressures through the use of the combined
analog outputs of up to 3 sensors.
• Using averaged analog output from up to 3 Capacitance Manometers with the same range for
critical process control.
• Fast relay control by a Cold Cathode sensor for high vacuum protection.

946 Controller Instruction Manual pg. 20
5 MKS Series 946 Vacuum System Controller
The MKS Series 946 Vacuum System Controller provides accurate and reliable pressure measurement
between 110-11 Torr to 110+5 Torr, measurement and control of mass flow rate, and control of system
pressure with MFC or pressure control valves. A number of different MKS pressure sensors, mass flow
controller/meters and control valves can be connected to the 946.
• MKS Baratron Capacitance Manometers with heads from 0.02 to 10,000 Torr (up to 6)
• MKS 423 I-Mag or Series 431/422 Cold Cathode sensors (up to 3)
• MKS Low Power Nude gauge or Mini BA Hot Cathode sensors (up to 3)
• MKS Series 317 Convection Pirani sensors (up to 6)
• MKS Series 275 Convectron sensors (up to 6)
• MKS Mass Flow controllers (up to 6), Types G, I, P Series with tied grounds and legacy products,
requiring +/- 15 to + 24VDC, 0-5 VDC set point and standard 15 pin or 9 pin D-sub cable
connection MKS 179A, M100MB Mass Flow Meters (up to 6)
• MKS 148, 248, and 154 upstream Solenoid Control Valves (1)
• MKS 153/T3B downstream Throttle Valves (1)
Figure 5-1 946 Front View
With 3 module slots available and the ability to configure a variety of sensor combinations, the Series 946
Vacuum System Controller can accommodate many unique requirements and applications. It is designed
with versatility and ease-of-use in mind, with a large LCD screen that displays: