MKS Granville-Phillips Mini-Convectron 275... User manual

Granville-Phillips®Mini-Convectron®Module
with RS-485 Interface
Instruction Manual
Instruction manual part number 275955
Revision F - November 2016
Series 275

Granville-Phillips®Mini-Convectron®Module
with RS-485 Interface
Series 275
Instruction Manual
Customer Service / Technical Support:
MKS Pressure and Vacuum Measurement Solutions
MKS Instruments, Inc., Granville-Phillips®Division
6450 Dry Creek Parkway
Longmont, Colorado 80503 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
MKS Corporate Headquarters
MKS Instruments, Inc.
2 Tech Drive, Suite 201
Andover, MA 01810 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
© 2016 MKS Instruments, Inc. All rights reserved.
Granville-Phillips®and Convectron®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.

This instruction manual is for use only with the following catalog numbers:
Catalog numbers for Series 275 Mini-Convectron Modules
with RS-485 Interface
Mini-Convectron Module with: Catalog #
1/8 NPT / 1/2 inch tubulation 275944
1/4 inch VCR-type female fitting 275945
1/2 inch VCR-type female fitting 275946
3/8 inch VCO-type male fitting 275947
1.33 inch (NW16CF) ConFlat-type flange 275948
2.75 inch (NW35CF) ConFlat-type flange 275949
NW10KF flange 275950
NW16KF flange 275951
NW25KF flange 275952
NW40KF flange 275953
NW50KF flange 275954
VCR & VCO are registered trademarks of Swagelok Company.
Instruction Manual

Mini-Convectron Module with RS-485 5
Instruction Manual - 275955
Table of Contents
Chapter 1 Safety and Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1 Safety Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 Reading and Following Instructions . . . . . . . . . . . . . . . . . . 8
1.3 Explosion / Implosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4 System Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.5 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.6 Service Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.7 Receiving Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Domestic Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
International Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Damaged Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.8 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapter 2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1 Important Precautions for Mini-Convectron Installation . . . 15
2.2 Mounting Location and Orientation . . . . . . . . . . . . . . . . . . 16
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Compression Mount/Quick Connect . . . . . . . . . . . . . . . . . . 19
1/8 NPT Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
NW or Flange Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ConFlat Flange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.5 I/O Connector Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.6 RS-485 Network Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2 Front Panel Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.3 Digital Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Syntax/Address Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 23
RS-485 Address Switch Settings . . . . . . . . . . . . . . . . . . . . . 23
Baud Rate, Stop Bit and Parity . . . . . . . . . . . . . . . . . . . . . . . 23
Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Interface Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . 24
ReaD Convectron pressure response . . . . . . . . . . . . . . . . . . 25
Set Offset Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Set span (typically at atmospheric pressure) . . . . . . . . . . . . 26
Set zero (at or near vacuum) . . . . . . . . . . . . . . . . . . . . . . . . 27
Set factory default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Set baud rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Set parity to 8 bits, none . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Set parity to 7 bits, odd . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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Instruction Manual - 275955
Set parity to 7 bits, even . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Set frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Reset module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
RX, TX Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Chapter 4 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Vacuum Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Atmosphere Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.2 Use with Gases other than N2and Air . . . . . . . . . . . . . . . . . 32
Chapter 5 Service/Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.1 Service Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.2 Mini-Convectron Disassembly . . . . . . . . . . . . . . . . . . . . . . 41
5.3 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Reset the Module to Factory Defaults . . . . . . . . . . . . . . . . . 43
5.4 Convectron Gauge Bakeout Instructions . . . . . . . . . . . . . . . 44
5.5 Cleaning a Convectron Gauge . . . . . . . . . . . . . . . . . . . . . . 44
5.6 Returning a Mini-Convectron Module for Service . . . . . . . . 45

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Chapter 1 Safety and Introduction
1.1 Safety Introduction START BY READING THESE IMPORTANT SAFETY INSTRUCTIONS AND
NOTES collected here for your convenience and repeated with additional
information at appropriate points in these instructions.
NOTE: These instructions do not and cannot provide for every contingency
that may arise in connection with the installation, operation, or
maintenance of this product. If you require further assistance, contact MKS,
Granville-Phillips Division at the address on the title page of this manual.
This product was designed and tested to offer reasonably safe service
provided it is installed, operated, and serviced in strict accordance with
these safety instructions.
In these instructions the word “product” refers to the Mini-Convectron
Module and all of its approved parts and accessories.
The instructions in this User Manual explain how to install, operate, and
maintain the Granville-Phillips®Mini-Convectron®vacuum gauge module.
•This chapter explains the caution and warning statements used
throughout the manual which must be adhered to at all times, your
responsibility to read and follow all instructions, how to contact customer
service, and product specifications.
•Chapter 2 explains how to install and connect the module.
These safety alert symbols in this manual
or on the Product rear panel, mean
caution − personal safety, property
damage or danger from electric shock.
Read these instructions carefully.
Failure to comply with these instructions may result
in serious personal injury, including death, or
property damage.
Table 1-1 Terms Describing the Mini-Convectron Module and Components
Term Description
Module The Mini-Convectron vacuum gauge module, which
contains a Convectron convection-enhanced Pirani
heat-loss pressure gauge.
Convectron Gauge The Convectron convection-enhanced Pirani heat-loss
gauge, which measures pressure within the vacuum
chamber.

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8Mini-Convectron Module with RS-485
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•Chapter 3 explains the theory of operation, how to operate the module,
and the RS-485 Interface commands.
•Chapter 4 explains calibration and using the module with gases other
than N2or Air.
•Chapter 5 explains troubleshooting, Convectron gauge testing, removal
and replacement, and module return-for-repair procedures.
1.2 Reading and
Following
Instructions
You must comply with all instructions while you are installing, operating,
or maintaining the module. Failure to comply with the instructions violates
standards of design, manufacture, and intended use of the module. MKS
Instruments, Inc. disclaims all liability for the customer's failure to comply
with the instructions.
•Read instructions – Read all instructions before installing or operating the
product.
•Follow instructions – Follow all installation, operating and maintenance
instructions.
•Retain instructions – Retain the instructions for future reference.
•Heed warnings and cautions – Adhere to all warnings and caution
statements on the product and in these instructions.
Parts and accessories – Install only those replacement parts and accessories
that are recommended by Granville-Phillips. Substitution of parts is
hazardous.
caution
Caution statements alert you to hazards or unsafe
practices that could result in minor personal injury or
property damage.
Each caution statement explains what you must do to prevent or
avoid the potential result of the specified hazard or unsafe
practice.
warning
Warning statements alert you to hazards or unsafe
practices that could result in severe property damage or
personal injury due to electrical shock, fire, or explosion.
Each warning statement explains what you must do to prevent
or avoid the potential result of the specified hazard or unsafe
practice.

Safety and Introduction
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Safety and Introduction
Caution and warning statements comply with American Institute of
Standards Z535.1–2002 through Z535.5–2002, which set forth voluntary
practices regarding the content and appearance of safety signs, symbols,
and labels.
Each caution or warning statement explains:
a. The specific hazard that you must prevent or unsafe practice that you
must avoid,
b. The potential result of your failure to prevent the specified hazard or
avoid the unsafe practice, and
c. What you must do to prevent the specified hazardous result.
1.3 Explosion /
Implosion
warning
The fumes from solvents such as trichloroethylene,
perchloroethylene, toluene, and acetone can be
dangerous to health if inhaled. Use only in well
ventilated areas exhausted to the outdoors. Acetone and
toluene are highly flammable and should not be used
near an open flame or energized electrical equipment.
warning
If used improperly, Mini−Convectron Gauges can
supply misleading pressure indications that can result in
dangerous overpressure conditions within the system.
Do not operate in an explosive atmosphere.
Do not operate the product in the presence of flammable
gases or fumes.
Operation of any electrical instrument in such an
environment constitutes a definite safety hazard.
Do not use the product to measure the pressure of
explosive or combustible gases or gas mixtures. The
sensor wire of the Mini−Convectron Gauge normally
operates at only 125 ˚C, but it is possible that Controller
malfunction can raise the sensor temperature above the
ignition temperature of combustible mixtures.
Danger of explosion or inadvertent venting to
atmosphere exists on all vacuum systems which
incorporate gas sources or involve processes capable of
pressurizing the system above safe limits.

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Danger of injury to personnel and damage to equipment exists on all
vacuum systems that incorporate gas sources or involve processes capable
of pressuring the system above the limits it can safely withstand.
For example, danger of explosion in a vacuum system exists during
backfilling from pressurized gas cylinders because many vacuum devices
such as ionization gauge tubes, glass windows, glass belljars, etc., are not
designed to be pressurized.
Series 275 instruments are furnished calibrated for N2. They also measure
the pressure of air correctly within the accuracy of the instrument. Do not
attempt to use a Series 275 Gauge calibrated for N2to measure or control
the pressure of other gases such as argon or CO2, unless accurate
conversion data for N2to the other gas is properly used. See Use with Gases
other than N2and Air beginning on page 32.
A pressure relief valve should be installed in the system if the possibility of
exceeding 1000 Torr (1333 mbar) exists.
Suppliers of pressure relief valves and pressure relief disks can be located
via an online search, and are listed at ThomasNet.com under “Relief
Valves”. Confirm that these safety devices are properly installed before
installing the product.
In addition, check that (1) the proper gas cylinders are installed, (2) gas
cylinder valve positions are correct on manual systems, and (3) the
automation is correct on automated systems.
warning
If accurate conversion data is not used, or is improperly
used, a potential overpressure explosion hazard can be
created under certain conditions. Using the N2
calibration to pressurize a vacuum system above about 1
Torr with certain other gases can cause dangerously
high pressures which may cause explosion of the system.
See Chapter 4, Calibration, before using the
Mini−Convectron vacuum gaugewith other gases.

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Safety and Introduction
1.4 System Grounding Grounding, though simple, is very important! Be certain that ground circuits
are correctly used on your ion gauge power supplies, gauges, and vacuum
chambers, regardless of their manufacturer. Safe operation of vacuum
equipment, including the Mini-Convectron Module, requires grounding of
all exposed conductors of the gauges, the controller and the vacuum
system. Lethal Voltages may be established under some operating
conditions unless correct grounding is provided.
Ion producing equipment, such as ionization gauges, mass spectrometers,
sputtering systems, etc., from many manufacturers may, under some
conditions, provide sufficient electrical conduction via a plasma to couple
a high voltage electrode potential to the vacuum chamber. If exposed
conductive parts of the gauge, controller, and chamber are not properly
grounded, they may attain a potential near that of the high voltage electrode
during this coupling. Potential fatal electrical shock could then occur
because of the high voltage between these exposed conductors and ground.
1.5 Operation It is the installer's responsibility to ensure that the automatic signals
provided by the process control module are always used in a safe manner.
Carefully check manual operation of the system and the setpoint
programming before switching to automatic operation. Where an
equipment malfunction could cause a hazardous situation, always provide
for fail-safe operation. As an example, in an automatic backfill operation
where a malfunction might cause high internal pressures, provide an
appropriate pressure relief device.
1.6 Service Guidelines Some minor problems are readily corrected on site. If the product requires
service, contact the MKS, Granville-Phillips Division Technical Support
Department at 1-303-652-4400 or 1-800-776-6543 for troubleshooting
help over the phone.
If the product must be returned to the factory for service, request a Return
Material Authorization (RMA) from Granville-Phillips. Do not return
products without first obtaining an RMA. In some cases a hazardous
materials disclosure form may be required. The MKS/Granville-Phillips
Customer Service Representative will advise you if the hazardous materials
document is required.
When returning products to Granville-Phillips, be sure to package the
products to prevent shipping damage. Shipping damage on returned
products as a result of inadequate packaging is the Buyer's responsibility.

Chapter 1
12 Mini-Convectron Module with RS-485
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For Customer Service / Technical Support:
MKS Pressure and Vacuum Measurement Solutions
MKS Instruments, Inc., Granville-Phillips®Division
6450 Dry Creek Parkway
Longmont, Colorado 80503 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
MKS Corporate Headquarters
MKS Instruments, Inc.
2 Tech Drive, Suite 201
Andover, MA 01810 USA
Tel: [phone]
Fax: [phone]
Email: [email protected].
1.7 Receiving
Inspection
Domestic Shipments Inspect all material received for shipping damage.
Confirm that your shipment includes all material and options ordered. If
materials are missing or damaged, the carrier that made the delivery must
be notified within 15 days of delivery in accordance with Interstate
Commerce regulations in order to file a valid claim with the carrier. Any
damaged material including all containers and packing should be held for
carrier inspection. Contact our Customer Service Department, 6450 Dry
Creek Parkway, Longmont, Colorado 80503 USA (telephone
303-652-4400) if your shipment is not correct for reasons other than
shipping damage.
International
Shipments
Inspect all material received for shipping damage. Confirm that your
shipment includes all material and options ordered. If items are missing or
damaged the carrier making delivery to the customs broker must be notified
within 15 days of delivery.
If an airfreight forwarder handles the shipment and their agent delivers the
shipment to customs the claim must be filed with the airfreight forwarder.
If an airfreight forwarder delivers the shipment to a specific airline and the
airline delivers the shipment to customs the claim must be filed with the
airline, not the freight forwarder.

Safety and Introduction
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Safety and Introduction
Damaged Material Any damaged material, including all containers and packaging, should be
held for carrier inspection. Contact our Customer Service Department,
6450 Dry Creek Parkway, Longmont, Colorado 80503, USA (telephone
303-652-4400) if your shipment is not correct for reasons other than
shipping damage.
1.8 Specifications
Pressure Measurement
Measurement Range for Air or N2Torr 1 x 10–4 to 1000
mbar 1 x 10–4 to 1333
Pascal 1 x 10–2 to 1.33 x 105
Resolution Torr 1 x 10–4
mbar 1 x 10–4
Pascal 1 x 10–2
Measurements will change with different gases and mixtures. Do not use
the module with flammable or explosive gases. The module is factory
calibrated for use with Air or N2. It measures the pressure of air correctly
within the specified accuracy of the instrument. If the module will measure
the pressure of a gas other than Air or N2, you must calibrate the
Mini-Convectron Module for the process gas. See Use with Gases other
than N2and Air on page-32 in the Calibration Chapter.
To achieve accurate readings down to 1 x 10-4 Torr, periodic calibration at
below 1 x 10-5 Torr must be performed.
Temperature Limits
Operating Temperature +4 to +40 °C (+32 to +104 °F) ambient, non-condensing
Non-operating Temperature –40 to +70 °C (–40 to +158 °F)
Bakeout Temperature Range +85 °C maximum with electronics attached
+150 °C maximum with electronics removed
Power Requirements and Electrical Connections
Power Requirement 11.0 to 16.0 Vdc, 0.12 A
Must be protected against reversals, transients, or over-voltages.
I/O Connector 8-pin DIN type

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Convectron Gauge
Sensing Wire Filament Gold-plated tungsten (standard)
Internal Volume 40 cc (2.5 cu in.)
Materials Exposed to Vacuum 304 stainless steel, gold, borosilicate glass, kovar, alumina,
NiFe alloy, polyimide
Digital Interface
RS-485 2-wire or 4-wire
Baud Rate 300 baud to 38.4 Kbaud
Data Format 7-bits, even parity, 1 stop bit
7-bits, odd parity, 1 stop bit
8-bits, no parity, 1 stop bit

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Chapter 2 Installation
2.1 Important
Precautions for
Mini-Convectron
Installation
The following precautions in the use and installation of the
Mini-Convectron must be observed.
• It is recommended that the Mini-Convectron be installed with the port
oriented vertically downward to ensure that no system condensates or
other liquids collect in the gauge tube. The gauge tube axis must be
horizontal if it is to be used at pressures above 1 Torr. Although the gauge
tube will read correctly below 1 Torr when mounted in any position,
erroneous readings will result at pressures above 1 Torr if the tube axis is
not horizontal.
• Do not use a compression mount (quick connect) for attaching the
Mini-Convectron to the system in applications resulting in positive
pressures in the gauge tube. Positive pressures might blow the tube out of
a compression fitting and damage equipment and injure personnel. Pipe
thread or flange mounting systems should be used for positive pressure
applications. In any case, the absolute pressure in the Convectron gauge
tube should not exceed 1000 Torr.
• Do not mount the Mini-Convectron so that deposition of process vapors,
upon the internal surfaces of the gauge tube, may occur through
line-of-sight access to the interior of the gauge tube.
• Do not install the Mini-Convectron where high amplitudes of vibration
are present. Excessive vibration will cause forced convection at high
pressure giving erroneous readings.
• Do not install the gauge tubes where they will be subject to corrosive
gases such as mercury vapor or fluorine which will attack the gold plated
sensor.
• For greatest accuracy and repeatability the Mini-Convectron Module
should be located in a stable room temperature environment.
• All connections to the Mini-Convectron Module are to be made with
shielded cable. The shield or shields are to be connected to the connector
shell.

Chapter 2
16 Mini-Convectron Module with RS-485
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2.2 Mounting Location
and Orientation
• Cleanliness pays. Keep the port cover in place until just before
installation.
• For proper operation above about 1 Torr, install Mini-Convectron
Modules with the gauge axis horizontal (see Figure 2-1). Although the
gauge will read correctly below 1 Torr when mounted in any position,
erroneous readings will result at pressures above 1 Torr if the gauge axis
is not horizontal.
• Vibration causes convection cooling of the sensor and will result in high
pressure readings. Mount Mini-Convectron Modules where they will not
vibrate excessively.
• Orient the gauge to prevent condensation of process vapors on the
internal surfaces through line-of-sight access to its interior. If vapor
condensation is likely, orient the port downward to help liquids drain out.
Figure 2-1 Mini-Convectron Module Installation

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Location Where you mount the Mini-Convectron Module is critical to obtaining
reliable pressure measurements. Long tubing or other constrictions can
cause large errors in pressure readings. If you mount the gauge near the
pump, the pressure in the gauge may be considerably lower than in the rest
of the system. If you place the gauge near a gas inlet or other source of
contamination, the pressure in the gauge may be much higher than in the
rest of the system.
Environment To minimize temperature effects, locate pressure gauges away from internal
and external heat sources, in an area where the ambient temperature is
reasonably constant.
2.3 Grounding
Under certain conditions, dangerously high voltage can be conducted
through a gas directly to an ungrounded conductor almost as effectively as
through a copper wire. The ability of an electric current to flow through a
gas under certain circumstances poses a serious risk. Do not touch the
exposed pins on any gauge installed on a vacuum system when high voltage
is present.
The Convectron Gauge envelope may not be reliably grounded through its
vacuum connection. For safety, you must either add a separate ground wire,
or shield the envelope to prevent human contact.
Ground the gauge envelope by using a metal hose clamp on the gauge
connected by a #12 AWG (minimum size) copper wire to the grounded
vacuum chamber.
Figure 2-2 Grounding the Mini-Convectron Gauge
When high voltage is present, all exposed conductors
of a vacuum system must be maintained at Earth
ground.
#12 AWG copper wire

Chapter 2
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2.4 Dimensions
Figure 2-3 Mini-Convectron Module Physical Dimensions
Table 2-1 Vacuum Connections
Fitting Description Dimension H
1/8 NPT pipe thread
1/2 inch compression fitting
1/8 NPT pipe thread
1/2 inch quick connect/weld
25.4 mm (1.0 in.)
VCR-type female fitting 1/2 inch 4 VCR-type female fitting
1/2 inch 8 VCR-type female fitting
30.5 mm (1.2 in.)
38.1 mm (1.5 in.)
ConFlat-type flange 1.33 inch (NW16CF) ConFlat-type
2.75 inch (NW35CF) ConFlat-type
38.1 mm (1.5 in.)
38.1 mm (1.5 in.)
KF flange NW16KF flange
NW25KF flange
NW40KF flange
30.5 mm (1.2 in.)
30.5 mm (1.2 in.)
38.1 mm (1.5 in.)

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Compression
Mount/Quick Connect
Do not use for positive pressure applications. The gauge may be forcefully
ejected. The gauge port is designed to fit a standard 1/2 in.
compression/quick connect mounting such as an Ultra-Torr fitting. Insert
the gauge tube port into the compression fitting and finger-tighten the
compression ring. A light film of vacuum grease, such as Apiezon®, will
ensure sealing.
1/8 NPT Mount Fits standard 1/8 NPT female fitting. Wrap the threads of the gauge port with
thread seal tape and hand tighten. Do not use a wrench or tool. Tighten only
enough to achieve a seal.
NW or Flange Mount The KF mounting system requires O-rings and centering rings between
mating flanges. Tightening the wing nut will hold the flanges and the
aluminum flange clamp together. Maximum pressure for this style of
mounting system is 1000 Torr absolute.
ConFlat Flange To minimize the possibility of leaks with ConFlat®flanges, use high strength
stainless steel bolts and a new, clean OFHC copper gasket. Avoid
scratching the seal surfaces. To avoid contamination, do not use nonmetal
gaskets.
Finger tighten all bolts. Use a wrench to continue tightening 1/8turn at a
time in crisscross order, e.g., 1, 4, 2, 5, 3, 6, 4 until all flanges are in contact.
After contact, further tighten each bolt about 1/16 turn.
2.5 I/O Connector Wiring The DIN type connector has the pin assignments shown below.
Figure 2-4 Power and I/O Connectors

Chapter 2
20 Mini-Convectron Module with RS-485
Instruction Manual - 275955
2.6 RS-485 Network
Wiring
Connection between multiple controllers can easily be made by daisy
chaining gauge controllers together with the signal from the host computer
going into one connector then out the other to another gauge controller.
• The maximum total cable length is 4,000 ft.
• No more than 32 devices can be connected to one RS-485
communications line.
When an RS-485 network is in an idle state, all nodes are in listen (receive)
mode. Under this condition there are no active drivers on the network. To
maintain the proper idle voltage state, bias resistors must be applied at the
ends of the lines to force the data lines to the idle condition. Figure 2-5
illustrates the placement of bias resistors on a host computer for typical 5
volt and 24 volt systems.
Figure 2-5 Bias Resistor Placement on Host Controller