Panametrics DigitalFlow GM868 User manual

panametrics.com
Flow
910-193S Rev. F
Jul 2021
DigitalFlow™ GM868
Panametrics Multipurpose Ultrasonic Gas Flowmeter
Service Manual

Flow
panametrics.com
Copyright 2021 Baker Hughes company.
This material contains one or more registered trademarks of Baker Hughes Company and its subsidiaries
in one or more countries. All third-party product and company names are trademarks of their respective
holders.
DigitalFlow™ GM868
Panametrics Multipurpose Ultrasonic Gas Flowmeter
Service Manual
910-193S Rev. F
Jul 2021

ii
[no content intended for this page]

DigitalFlow™ GM868 Service Manual iii
Information Paragraphs
Note: These paragraphs provide information that provides a deeper understanding of the situation, but is not
essential to the proper completion of the instructions.
IMPORTANT: These paragraphs provide information emphasizing instructions which are essential to proper setup of
the equipment. Failure to follow these instructions carefully may cause unreliable performance.
Safety Issues
Auxiliary Equipment
Local Safety Standards
The user must make sure that he operates all auxiliary equipment in accordance with local codes, standards,
regulations, or laws applicable to safety.
Working Area
WARNING! Indicates a potentially hazardous situation which can result in serious personal
injury or death, if it is not avoided.
CAUTION! Indicates a potentially hazardous situation which can result in minor or moderate
injury to personnel or damage to the equipment, if it is not avoided.
HIGH VOLTAGE! This symbol indicates the presence of high voltage. It calls your attention to
situations or operations that could be dangerous to you and other persons operating the
equipment. Read these messages and follow the instructions carefully.
WARNING! It is the responsibility of the user to make sure all local, county, state and national
codes, regulations, rules and laws related to safety and safe operating conditions
are met for each installation.
WARNING! Auxiliary equipment may have both manual and automatic modes of operation. As
equipment can move suddenly and without warning, do not enter the work cell of
this equipment during automatic operation, and do not enter the work envelope of
this equipment during manual operation. If you do, serious injury can result.

iv DigitalFlow™ GM868 Service Manual
Qualification of Personnel
Make sure that all personnel have manufacturer-approved training applicable to the auxiliary equipment.
Personal Safety Equipment
Make sure that operators and maintenance personnel have all safety equipment applicable to the auxiliary
equipment. Examples include safety glasses, protective headgear, safety shoes, etc.
Unauthorized Operation
Make sure that unauthorized personnel cannot gain access to the operation of the equipment.
Environmental Compliance
Waste Electrical and Electronic Equipment (WEEE) Directive
Panametrics is an active participant in Europe’s Waste Electrical and Electronic Equipment (WEEE) take-back
initiative, directive 2012/19/EU.
The equipment that you bought has required the extraction and use of natural resources for its production. It may
contain hazardous substances that could impact health and the environment.
In order to avoid the dissemination of those substances in our environment and to diminish the pressure on the
natural resources, we encourage you to use the appropriate take-back systems. Those systems will reuse or recycle
most of the materials of your end life equipment in a sound way.
The crossed-out wheeled bin symbol invites you to use those systems.
If you need more information on the collection, reuse and recycling systems, please contact your local or regional
waste administration.
Visit www.bakerhughesds.com/health-safetyand-environment-hse for take-back instructions and more information
about this initiative.
WARNING! Make sure that power to the auxiliary equipment is turned OFF and locked out
before you perform maintenance procedures on the equipment.

DigitalFlow™ GM868 Service Manual v
Contents
Chapter 1. Calibration
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Menu Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.3 Calibrating the Analog Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Accessing the Calibration Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4.1 Calibrating the Low End of the Output Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4.2 Calibrating the High End of the Output Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4.3 Testing the Analog Output Linearity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Calibrating the Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5.1 Accessing the Calibration Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5.2 aLOW Option = [F1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5.3 aHIGH Option = [F2]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5.4 4 mA Option = [F3]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5.5 20 mA Option = [F4] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.6 Calibrating the RTD Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.6.1 Accessing the Calibration Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.6.2 Probe Option = [F1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.6.3 Numer Option = [F2] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.7 Testing the Alarm Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.7.1 Accessing the Calibration Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.8 Testing the Totalizer/Frequency Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.8.1 Accessing the Calibration Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.8.2 Entering Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
1.8.3 Entering Pulse Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 2. Error Codes and Screen Messages
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
2.2 E0: No Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3 E1: Low Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.4 E2: Sound Speed Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.5 E3: Velocity Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.6 E4: Signal Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.7 E5: Amplitude Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.8 E6: Cycle Skip, Accel.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.9 E7: Analog Out Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.10 E8: Temp In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.11 E9: Press In. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.12 E10: Special Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.13 E11: Not Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.14 E12: Not Used. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.15 E13: Over Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.16 E14: Totals Overflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.17 E15: Equation Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.18 Screen Messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Chapter 3. Diagnostics
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2 Displaying Diagnostic Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3 Diagnostic Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.4 Flowcell Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4.1 Gas Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4.2 Pipe Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.5 Transducer Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Chapter 4. Parts Replacement
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
4.2 Fuse Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
4.3 Removing the Printed Circuit Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Contents
vi DigitalFlow™ GM868 Service Manual
4.4 Replacing the EPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
4.5 Installing an Option Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
4.6 Replacing the LCD Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
4.7 Installing the Printed Circuit Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
4.8 Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Appendix A. Service Record
A.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
A.2 Data Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Appendix B. Optional Enclosures
B.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
B.2 Rack Mount Enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
B.3 Rack Mount Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
B.4 Rack Mount Option Card Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
B.5 Rack Mount EPROM Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
B.6 Rack Mount LCD Display Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
B.7 Rack Mount Printed Circuit Board Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
B.7.1 Circuit Board Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
B.7.2 Circuit Board Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

DigitalFlow™ GM868 Service Manual vii
Contents

Contents
viii DigitalFlow™ GM868 Service Manual

DigitalFlow™ GM868 Service Manual 1
Chapter 1. Calibration
Chapter 1. Calibration
1.1 Introduction
Calibrating the Model GM868’s analog outputs and inputs is explained in this chapter. In addition, testing the optional
totalizer/frequency and alarm relay outputs is discussed. The following specific topics are included:
• calibrating Slot 0-6 analog outputs
• calibrating Slot 1-6 analog inputs
• calibrating Slot 1-6 RTD inputs
• testing Slot 1-6 alarm relays
• testing Slot 1-6 totalizer/frequency outputs.
The Model GM868 electronics console includes six expansion slots for the installation of option cards. These slots are
numbered 1-6, from right to left. In addition, every Model GM868 flowmeter includes two built-in analog outputs (A
and B) at terminal block I/O, which is designated as Slot 0.
Note: Convention in this manual identifies any expansion slot as Slot x , where x is a number from 0-6.
See Chapter 1, Installation , of the Startup Guide for a complete description of the available option cards and the
procedures for wiring them.
1.2 Menu Map
The Calibration Menu is accessed by pressing the [CAL] key on the keypad. Use this menu to calibrate and test the
Slot 0 analog outputs, as well as to calibrate and test any option cards that are installed in the expansion slots. Refer
to the menu map in Figure 6 on page 15 as a guide in following the calibration instructions.
Note: The instructions on the next page apply to both the 1-Channel and 2-Channel versions of the Model GM868
flowmeter.
The following discussion assumes that the left screen pane is active. If the right screen pane is active, only the
function key designations change. That is, replace [F1]-[F4] with [F5]-[F8]. Proceed to the appropriate sections of
this chapter to calibrate and test all of the installed inputs and/or outputs.
Note: While in the Calibration Menu , if there is no keypad activity for two minutes, the Model GM868 will
automatically reboot and return to measurement mode.

Chapter 1. Calibration
2 DigitalFlow™ GM868 Service Manual
1.3 Calibrating the Analog Outputs
Every Model GM868 flowmeter includes two built-in analog outputs (A and B) at terminal block I/O, which is
designated as Slot 0. Additional analog outputs may be added to the Model GM868 by installing an
Analog Outputs
Option Card
in one (or more) of the six expansion slots. Each option card contains four analog outputs, which are
designated as A, B, C and D. Both the zero-point and full-scale values for each output must be calibrated. After
calibrating the outputs, which have a resolution of 5.0 A (0.03% full scale), their linearity should be tested.
Note: The zero point of the analog output may be set for either 0 mA or 4 mA. However, the calibration procedure
always uses the 4 mA point, as the meter will extrapolate this value to obtain the 0 mA point.
Prepare for the calibration procedure by connecting an ammeter to the desired analog output of Slot X, as shown in
Figure 1 below and Figure 2 on the next page. Refer to the menu map in Figure 6 on page 15.
Figure 1: Ammeter Connection for Slot 0 (Output A)
Terminal Block I/O (Slot 0)
B
RTN
B
SIG
A
RTN
A
SIG
41
+
-
Ammeter

DigitalFlow™ GM868 Service Manual 3
Chapter 1. Calibration
1.3 Calibrating the Analog Outputs (cont.)
Figure 2: Ammeter Connection for Slots 1-6 (Output A)
Terminal Block (Option Card)
A
SIG
A
RTN
B
SIG
B
RTN
D
SIG
D
RTN
C
SIG
C
RTN
+
-
Ammeter
1
8

Chapter 1. Calibration
4 DigitalFlow™ GM868 Service Manual
1.4 Accessing the Calibration Menu
1. Press the [CAL] key to enter the Calibration Program .
2. Press [Fx] to calibrate the desired slot. (The option bar will include a slot listing for each installed option card.)
3. Press [Fx] to select the desired output.
IMPORTANT: The procedure for calibrating all the outputs is the same. However, when calibrating a different output,
be sure to reconnect the ammeter to the appropriate pins on terminal block I/O. See Figure 1 on page 2
or Figure 2 above for the correct pin numbers.
1.4.1 Calibrating the Low End of the Output Range
1. Press [F1] to calibrate the low end of the output range.
2. Press [F1] or [F2] to adjust the ammeter reading UP or DOWN, until a 4 mA reading is achieved. If you press [F3],
Numer, enter a numeric value for the calibration point and press [ENT].
3. Press [F4] to STORE the setting, or press  and [F1] to ABORT the calibration.
Note: If the ammeter reading cannot be adjusted within 5.0  A of the 4 mA setting, contact the factory for
assistance.
1.4.2 Calibrating the High End of the Output Range
1. Press [F2] to calibrate the high end of the output range.
2. Press [F1] or [F2] to adjust the ammeter reading UP or DOWN, until a 20 mA reading is achieved. If you press [F3],
Numer, enter a numeric value for the calibration point and press [ENT].
Note: If the ammeter reading cannot be adjusted within 5.0  A of the 20 mA setting, contact the factory for
assistance.
3. Press [F4] to STORE the setting, or press  and [F1] to ABORT the calibration.
Note: Skip the next section if the linearity test will not be performed at this time. Proceed to Procedure Options on
the next page.
1.4.3 Testing the Analog Output Linearity
Note: If you exited this menu and are returning, follow steps 1 through 3 in Accessing the Calibration Menu on
page 4.
1. Press [F3] to TEST the linearity of the currently selected analog output.
2. Check the ammeter reading at the 50% output level.
3. Then, enter a different output level (0-100%) and press [ENT].
4. Check the ammeter reading at this setting and press [ENT] when done.
Table 1 on the next page lists the expected ammeter readings at various
% Full Scale settings, for both 4-20 mA and
0-20 mA scales. Refer to this table to verify the accuracy of the ammeter readings taken above.

DigitalFlow™ GM868 Service Manual 5
Chapter 1. Calibration
1.4.3 Testing the Analog Output Linearity (cont.)
If the linearity test readings are not within 5 A of the values listed in Table 1 above, check the accuracy and wiring of
the ammeter. Then, repeat the low and high end calibrations. If the analog output still does not pass the linearity test,
contact the factory for assistance.
Procedure Options
You have completed calibration of the analog output. Do one of the following:
• To calibrate or test another output, press [F4] (EXIT) and return to Step 3 in
Accessing the Calibration Menu on
page 4.
• To calibrate/test additional slots, press [F4] (EXIT) twice and proceed to the appropriate section.
• To leave the Calibration Menu, press [F4] (EXIT) three times.
Table 1: Expected Ammeter Readings
% Full Scale 4-20 mA Scale* 0-20 mA Scale*
0 4.000 0.000
10 5.600 2.000
20 7.200 4.000
30 8.800 6.000
40 10.400 8.000
50 12.000 10.000
60 13.600 12.000
70 15.200 14.000
80 16.800 16.000
90 18.400 18.000
100 20.000 20.000
* All ammeter readings should be ±0.005 mA

Chapter 1. Calibration
6 DigitalFlow™ GM868 Service Manual
1.5 Calibrating the Analog Inputs
Analog inputs may be added to the Model GM868 flowmeter by installing an Analog Inputs Option Card in one (or
more) of the six expansion slots. The option card contains two analog inputs, which are designated as A and B. Each
of the inputs, which may be either a 0/4-20 mA input or an RTD input, must be calibrated at both the zero-point and
full-scale values. After calibrating the inputs, their linearity should be tested.
Calibration of the analog inputs requires the use of a calibrated current source. If an independent calibrated current
source is not available, one of the Slot 0 analog outputs may be used for the calibration. During the analog input
calibration, the Slot 0 analog output will supply the low reference, high reference, 4 mA and 20 mA signals at the
appropriate times.
Note: If a Slot 0 analog output will be used to calibrate the analog inputs, make sure that the Slot 0 analog output
calibration procedure has already been completed.
Connect the Slot 0 analog output(s) (or an independent calibrated current source) to the analog input(s) on the
option card, as shown in Figure 3 below. Refer to the menu map in Figure 6 on page 15 as a guide.
Figure 3: Analog Input Calibration Connections
Analog Input Option Card
A
INHI
A
+24V
A
RTN
A
INLO
B
RTN
B
INLO
B
INHI
B
+24V
1
8
RTN
4
Terminal Block I/O (Slot 0)
RTNSIG
BB
SIG
AA
1

DigitalFlow™ GM868 Service Manual 7
Chapter 1. Calibration
1.5 Calibrating the Analog Inputs (cont.)
For this discussion, assume that the option card has been installed in Slot x.
Note: The zero point of the analog input may be set for either 0 mA or 4 mA. However, the calibration procedure
always uses the 4 mA point, as the meter will extrapolate this value to obtain the 0 mA point.
1.5.1 Accessing the Calibration Menu
1. Press the [CAL] key to enter the Calibration Program .
2. Press [Fx] to calibrate the desired slot. (The option bar will include a slot listing for each installed option card.)
3. Press [Fx] to select the desired input.
The procedure for calibrating Input A is identical to that for calibrating Input B. However, when calibrating Input B, be
sure a calibrated current source is connected to the appropriate pins on the terminal block. See Figure 3 on the
previous page for the correct pin numbers. To calibrate a 0/4-20 mA input card, see the section below.
Note: To calibrate an RTD input card, refer to page 9.
4. Press [F1]-[F4] to select the reference point to be calibrated.
Do one of the following:
• If you selected [F1] (aLOW), proceed to aLOW Option on the next page.
• If you selected [F2] (aHIGH), proceed to aHIGH Option on the next page.
• If you selected [F3] (4 mA), proceed to 4 mA Option on the next page.
• If you selected [F4] (20 mA), proceed to 20 mA Option on the next page.

Chapter 1. Calibration
8 DigitalFlow™ GM868 Service Manual
1.5.2 aLOW Option = [F1]
1. Enter the low reference value and press the [ENT] key.
2. Press [F1] to store the current low reference value or press [F2] to cancel the entry. In either case, the ANALOG
INPUT prompt will reappear.
3. Press [F2] to proceed to the next section.
1.5.3 aHIGH Option = [F2]
1. Enter the high reference value and press the [ENT] key.
2. Press [F1] to store the current high reference value or press [F2] to cancel the entry. In either case, the ANALOG
INPUT prompt will reappear.
3. Proceed to Procedure Options below.
1.5.4 4 mA Option = [F3]
1. Connect the 4 mA current source to the currently selected analog input, as shown in Figure 3 on page 6.
2. Press [F1] to store the current 4 mA value or press [F2] to cancel the entry. In either case, the ANALOG INPUT
prompt reappears.
3. Press [F4] to proceed to the next section.
1.5.5 20 mA Option = [F4]
1. Connect the 20 mA current source to the currently selected analog input, as shown in Figure 3 on page 6.
2. Press [F1] to store the current 20 mA value or press [F2] to cancel the entry. In either case, the ANALOG INPUT
prompt reappears.
3. Proceed to Procedure Options below.
Procedure Options
You have completed calibration of the analog output. Do one of the following:
• To calibrate another input, return to Step 3 in
Accessing the Calibration Menu on the previous page.
• To calibrate/test additional slots, press [F4] (EXIT) and proceed to the appropriate section.
• To leave the Calibration Menu, press [F4] (EXIT) twice.

DigitalFlow™ GM868 Service Manual 9
Chapter 1. Calibration
1.6 Calibrating the RTD Inputs
Calibrating an RTD option card involves a different procedure than for other analog input cards. However, you access
the card in the same manner as other cards.
1.6.1 Accessing the Calibration Menu
1. Press the [CAL] key to enter the Calibration Program .
2. Press [Fx] to calibrate the desired slot. (The option bar will include a slot listing for each installed option card.)
If you have installed an RTD option card, the following screen appears:
The Probe option allows the meter to calculate the temperature vs. resistance curve, based on input from the RTD in
a temperature bath or from an RTD calibrator. The Numer option forces the user to calculate and input the curve
values numerically.
IMPORTANT: Use only one option for RTD calibration. Do not try to calibrate with both options.
1.6.2 Probe Option = [F1]
1. Press [F1] to select Input A, or [F2] to select Input B.
1.6.2.1 Set Point Temperature
1. Press [F1] to enter the set point temperature (formerly known as the zero point). This temperature should be at
the low end of your expected operating range.
2. Enter the desired set point temperature, and press [ENT].
3. Press [F1] to STORE the entered temperature, or [F2] to ABORT the calibration. In either case, the screen returns
to the ANALOG INPUT prompt.
1.6.2.2 Slope Point Temperature
1. Press [F2] to enter the slope point temperature. This temperature should be as far from your set point as your
temperature bath will allow, within the range -100° to +350°C.
2. Enter the desired slope point temperature, and press [ENT].
3. Press [F1] to STORE the entered temperature, or [F2] to ABORT the calibration. In either case, the screen returns
to the ANALOG INPUT prompt.
4. Proceed to Procedure Options on the next page.
1.6.3 Numer Option = [F2]
The Numer option forces the user to calculate the temperature vs. resistance information. To do this, the user must
first collect data using the RTDs option in the PRINT menu (discussed in Chapter 5 of the
Programming Guide ). The
RTDs option allows you to know what point value the GM868 is reading at a given temperature. With this information,
the Numer option enables you to enter the Set Temperature and the slope of the RTD input in points/degree, allowing
absolute control over RTD calibration. Before attempting this step, follow the instructions in Chapter 5 of the
Programming Manual (“The RTDs Submenu”) to obtain point values at your set point and slope point.
1. Press [F1] to select Input A, or [F2] to select Input B.
1.6.3.1 Set Number
1. Press [F1] to enter the set number (formerly known as the zero point).
2. Enter the set point temperature, and press [ENT].
CALIBRATION Press [F1] to select the Probe method of calibration, or [F2] to select the
numeric method.
Slot x Inputs
current input selected
RTD CALIBRAT
last option selected
Probe Numer

Chapter 1. Calibration
10 DigitalFlow™ GM868 Service Manual
3. The program then asks for the set point number. Enter the points measured at the set temperature, and press
[ENT].
1.6.3.2 Slope Number
1. Press [F2] to enter the slope number. Calculate the slope number with the formula:
Slope=Slope points - set points
slope temp - set temp
2. Enter the RTD slope number and press [ENT].
Procedure Options
You have completed calibration of the RTD input. Do one of the following:
• To calibrate another input, press [EXIT].
• To calibrate additional slots, press [EXIT] and then [F4] (EXIT) and proceed to the appropriate section.
• To leave the Calibration Menu, press [F4] (EXIT) twice.