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