Ground Master®

Equipment Ground MonitorsModels CTC065

CTC065RT

User’s GuideCredence Technologies, Inc.

Master Unit Slave Unit 4..20mA Conf.

GND1 GND2 GND3 GND4 Output, mAGood Good Good Good 20Failed Good Good Good 18Good Failed Good Good 17Failed Failed Good Good 16Good Good Failed Good 15Good Good Good Failed 14Good Good Failed Failed 13Failed Good Failed Good 12Good Failed Failed Good 11Failed Failed Failed Good 10Failed Good Good Failed 9Good Failed Good Failed 8Failed Failed Good Failed 7Failed Good Failed Failed 6Good Failed Failed Failed 5Failed Failed Failed Failed 4

4 5 7 8 RJ45 Pin5,6,7,8 1,2,3,4 Master Unit

Grounds5,6,7,8 1,2,3,4 Slave Unit

Limited WarrantyCredence Technologies, Inc. warrants Ground Master monitors to be free from defects in materials andworkmanship under normal use and service for a period of one (1) year from date of purchase directlyfrom Credence Technologies, Inc., or from its authorized distributors. This warranty extends only to theoriginal purchaser. This warranty shall not apply to any product or part of it which has been subjectedto misuse, neglect, accident or abnormal conditions of operation. Except to the extent precluded byapplicable state law, Credence Technologies will have no liability for any consequential, incidental, orspecial damages.

In the event of failure of a product covered by this warranty, Credence Technologies, Inc. will repair aproduct returned to authorized distributor or, only if it was purchased directly from Credence Technolo-gies, Inc., to the manufacturer; provided the warrantorís examination discloses to the company’s satis-faction that the product was defective and is qualified for to a warranty claim. Credence Technologiesmay, at its option, replace the product or its components with new or factory-refurbished parts or aswhole in lieu of repair. With regard to a product returned within one year of its purchase, said repair orreplacement will be made without charge. If the failure has been caused by misuse, neglect, accident orabnormal conditions of operation, repairs will be billed at a nominal cost. Warranty does not covertransportation costs.

Credence Technologies, Inc.3601-A Caldwell Dr.

Soquel, CA 95073 U.S.A.Tel. 831-459-7488 FAX 831-427-3513www.credencetech.com

© 2004 Credence Technologies, Inc.

Ground Masteris registered trademarkof Credence Technologies, Inc.Patent Pending. Made in U.S.A.

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Welcome to Ground Master®! Now you will know at all times whetheryour equipment is properly grounded, assuring ESD safety of yourprocess.

Ground Master® is a comprehensive real-time ground monitor thatchecks connection of your equipment to ground in accordance withANSI/ESDA S.20.20 standard. It also monitors presence ofelectromagnetic interference (EMI) on ground, alerting you topossible functionality problems, such as tool lockups, erraticbehavior, parametric errors, etc.

Controls and IndicatorsPower LED Indicates that power is provided for

operation of Ground Master®

Pass/Fail LEDs Indicates which ground is being monitoredand whether each ground quality iscompliant or non-compliant with yourrequirements

Enable Switches Enables/disables monitoring of eachindividual ground connection

Sound On/Off Enables/disables alarm buzzer

Fuses Replaceable safety fuses for each individualground connection

Equipment Terminals Screw terminals for connection of theindividualequipment grounds

Ground Connection Terminal for connection to reference ground

Power Jack for power adapter

Output RJ45 jack for connection to facilitymonitoring system 4..20mA or MODBUS

Ext. RJ45 jack for connection to an extension/slave or MODBUS

Operation with Facility Monitoring SystemGround Master provides intelligent information to a facility monitor-ing system (FMS) or data acquisition system (DAQ) on status of eachindividual ground it monitors.

System RequirementsDAQ or FMS must be able to sample data from each Ground Mas-ter monitor often enough in order not to miss intermittent groundingproblems and to properly represent them. Credence Technologiescan provide you with the portable or stationary data acquisition sys-tems if you don’t already have one -- please contact the factory orauthorized distributor.

Ground Master provides output signal via its RJ45 connector.

F IMPORTANT: DO NOT PLUG GROUND MASTER INTO YOUR10/100BASET ETHERNET FACTORY NETWORK!

If a long data cable is used, it is advisable to install ferrite clamp-onchokes on both ends of the cable in order to reduce electromagneticinterference induced on cables. Please contact the factory for properselection of ferrite filters.

WARNING! FAILURE TO FOLLOW THESE INSTRUCTIONS MAYRESULT IN IRREVERSIBLE DAMAGE TO GROUND MASTER ANDMAY HARM PERSONNEL AND EQUIPMENT!

If Ground Master is connected to a Facility Monitoring System(FMS), always verify that there is zero voltage and low resistancebetween FMS ground and ground at the location where GroundMaster is being grounded. If ground conditions are unaccept-able, correct them prior to installing Ground Master, otherwisedamage to personnel, Ground Master and/or FMS may occur.

Signal LevelsFor MODBUS interface contact factory for specific details. For4..20mA each connection provides information on four grounds --please see section “Data Output.” Each Ground Master has twosuch groups of grounds -- grounds 1..4 and grounds 5..8. For eachgroup, the table below shows the output current corresponding tothe different states of the grounds. For a Facility Monitoring Systemto generate an alarm, it is recommended to set it to 19 mA outputsignal since below this level there is at least one failure condition.

2 11

Supp

lyPo

wer

Pow

er L

ED

Fuses

Brief Tour of your Ground MasterPlease refer to the rest of this User’s Guide for detailed explanationof each control, indicator and connection.

4..2

0mA

to F

MS

or M

OD

BUS

Pow

er A

dapt

er

Exte

nsio

n/sla

ve (4

..20m

A)or

MO

DBU

S

Equi

pmen

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min

als

Refe

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roun

dC

onne

ctio

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Equi

pmen

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Enable SwitchesSound On/OffSwitch

Pass/FailLEDs

Out

puts

toth

e to

ol

For Ground Master RT

Alarm LimitsEach Ground Master is calibrated to provide alarm when imped-ance of the equipment to ground goes above the preset limit. Thislimit is set at the factory and can be changed using the rotary switchon the top of the unit with the small screwdriver.

Setting 1 2 3 4 5 6 7 8 9 A B C D E F

Limit 1 2 3 4 5 6 7 8 9 10 12 14 16 18 20(Ohms)

“0” setting is reserved -- do not use it.

Don’t forget to account for impedance of wires from Ground Masterto your equipment and to ground.

It is tempting to try to comply with the lowest possible impedancelimits, such as 1 Ohm. However, very seldom this can be achievedin a realistic factory environment. Even the wires between themonitor and the equipment have finite impedance. Start first withthe more achievable levels, such as 10 Ohms, and once it is achieved,reduce the alarm threshold down to the next practical level.

FusesIf equipment ground is disconnected for whatever reason, or theground wiring is done improperly, such equipment may be under

significant potential, some-times equal to the voltageon the AC mains (110V or220V). In order toprevent propagation of thisvoltage to other equipmentvia Ground Master, fusesare implemented for each

individual ground connection. In case of excessive voltage on theequipment, appropriate fuse will disconnect the equipment fromGround Master and from the other connected equipment. Groundfailure on that particular ground will be immediately indicated.

Before replacing the fuse always investigate the reason for fuse blow-ing and correct the problem. Fuse should never be blown undernormal circumstances.

F IMPORTANT: NEVER USE WIRE JUMPERS IN PLACE OF FUSES -- USE ONLY FACTORY-AUTHORIZED FUSES. DISCONNECTPOWER BEFORE REPLACEMENT OF FUSES.

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OverviewGround Master® is a continuous monitor of grounding status of equip-ment. It provides independent ground monitoring of up to 8 tools.Monitoring of ground connection is done in according toANSI/ESDA S.20.20 standard. Specific limits are set to the customerrequirements. If no requirements are specified, default ground im-pedance set at the factory to 10 Ohms.

In addition to monitoring connection to ground, Ground Masteroffers monitoring of electromagnetic interference (EMI) on the groundwires often present in a factory environment. Such interference causesproblems with operation of equipment.

Ground Master provides local indication and alarm of the status ofeach ground and local alarms. In addition, Ground Masterprovides intelligent output to a facility monitoring or data acquisitionsystem for factory-wide monitoring.

To extend monitoring to additional 8 points, another Ground Mastermonitor can be connected to the extension port. Connected unitswould provide one combined output to a facility monitoring system.

Safety First!

While assuring proper ESD grounding is a purpose of usingGround Master, before connecting equipment to it make surethat equipment itself is properly grounded. Ground Master onlyMONITORS proper connection to ground. DO NOT groundequipment through Ground Master.

OperationMonitoring EnableIn order for Ground Master to moni-tor a particular ground, it must beenabled by turning “on” (sliding up)the appropriate DIP switch. Thisway you won’t need to use wirejumper to simulate unused connec-tion and will always know the status of every ground connection.

If you are not planning to monitor a particular connection, turn theappropriate switch “off” by sliding it down.

IndicationWhen ground moni-toring is enabled onany particular ground,one of the correspond-ing LEDs lights on. Ifthe ground connectionis within the specification, the green LED be lit. If the ground imped-ance is higher than the limit, the red LED will be on. In case theground connection impedance is below the alarm limit, but theparticular ground has strong EMI signal present, the green LED willbe on and the red LED will be blinking.

Summary of LED Indication:

Status Green LED Red LED Sound

Ground impedance passes On Off Off

Ground impedance fails Off On OnGround impedance passes On Blinks Offbut strong EMI present

Ground monitoring disabled Off Off Off

Sound can be turned on/off using the slide switch.

Monitoring Enable Switches

Ground Status Indication

4 9

Installation and ConnectionsPlacementMount Ground Master on a wall or on a side of equipment where itsstable placement and access to all connections is assured. DIN-railmounting is available as well. Place Ground Master so that thelength of wires to the monitored equipment is minimized.

MountingDepending on the mounting option that you have ordered, GroundMaster comes with the bracket to mount it on a flat surface. Anoptional DIN bracket to mount it on a standard DIN rail is available.

Connecting Reference GroundGround Master must be connected to proper facility ground using itsGND connection. This ground will serve as a reference. Without thisconnection no monitoring is possible.

Make sure that this referenceground is a true ground andis properly connected to bothfacility (power) ground and toESD ground, should such beseparately present at yourfactory.

Crimp 18 AWG (1mm diam-eter) wire to the supplied ringterminal and connect it to theGND terminal of the unit. Connect the other end of this wire toproper facility ground. Minimize the length of this wire since theimpedance of this wire will be a significant factor in measuring groundimpedance of all connections. Do not coil extra length of this wire.

Connecting Equipment GroundsUse 18 AWG (1mm diameter) wires to connect them to the screwterminals of the unit. Connect the other end of the wire to groundedconnection of your equipment.

Shorten the wires and do not coil or loop extra wire. The longer thewire, the higher its impedance and the more influence it will makeon the monitored parameters.

GNDRingTerminal

GroundWire

Screw

Lockwasher

Connection to Main Ground

Connecting two Ground Master Units TogetherIn cases when more than 8 ground connections must be monitored,you can connect two Ground Master units in Master/Slave configu-ration as shown. This configuration isvalid only for Ground Master with4..20mA outputs. For connectingGround Masters with MODBUS inter-face follow MODBUS conventions.

The cable that connects both units mustbe 100BASE-T4CROSSOVER RJ45CABLE -- please consult the factory, yourcomputer administrator or computerstore. Do not use regular RJ45 cableor regular 10/100 Base T crossovercable. Crossover cables usually havered or orange color of insulation, how-ever do not rely on color only.

The slave Ground Master unit gets itspower from the master unit. Do not plug power adapter into theslave unit.

Only one slave unit can be connected to the master unit to monitorup to a total of 16 grounds. Do not connect any other monitors tothe slave unit.

FUSE FUSE FUSE FUSE FUSE FUSE FUSE FUSE

Mad

e in

U.S

.A.

Pate

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ng

Sound

Ground Master R

Ground Enable

Power

6 7 81 2 3 4 5

1 2 3 4 5 6 7 8GND

1 2 3 54 6 7 8

Output PowerExt.

Equipment Ground Monitor

CredenceTechnologies

Before replacing fuses, disconnect the power

Fail

Good

On

Off

FUSE FUSE FUSE FUSE FUSE FUSE FUSE FUSE

Mad

e in

U.S

.A.

Pate

nt P

endi

ng

Sound

Ground MasterR

Ground Enable

Power

Output to FacilityMonitoring System

PowerAdapter

6 7 81 2 3 4 5

1 2 3 4 5 6 7 8GND

1 2 3 54 6 7 8

Output PowerExt.

Equipment Ground Monitor

CredenceTechnologies

Before replacing fuses, disconnect the power

Fail

Good

Crossover RJ45 Cable

On

Off

Master UnitSlave Unit

Connection of Ground Master monitorsin Master/Slave Configuration

100 BASE-T4 crossovercable diagram

Pin# Pin#1 <> 32 <> 63 <> 14 <> 75 <> 86 <> 27 <> 48 <> 5

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As a reference, DC resistance of an 18 AWG wire is 0.0128 Ohms/meter or 0.00387 Ohms/ft. This doesn’t take into accountresistance of the connection nor AC impedance component whichcould be significant if the wire is coiled.

Connecting PowerGround Master can be powered in the following ways:

by a separate power adapter

via its RJ45 cable from facility monitoring system forGround Master

via terminal block for Ground Master RT

F IMPORTANT: PROVIDE POWER VIA ONE WAY ONLY.

Ground Master needs 12..24V DC and consumes less than 300 mA

If two Ground Master monitors are connected together (see furtherin the text), the “slave” monitor gets power from the “master” unitand the current requirements double.

Power Jack: it is a 2.1mm barrel connector, center positive

RJ45 Jack: See pinouts for your configuration.

Power must be reasonably clean of spikes and EMI. Use only poweradapter provided or approved by Credence Technologies.

Data Output (Ground Master)Ground Master provides intelligent information to facility monitoringor data acquisition system. Ground Master can be ordered in twoversions -- 4..20mA or MODBUS. In either configuration GroundMaster can be powered by facility monitoring system (FMS) via itsdata cable.

Pinout of RJ45 Jack for 4..20mA

Pin Signal1 +12..24V DC2 Ground3 +12..24V DC4 Output grounds 5..8, master unit5 Output grounds 1..4, master unit6 Ground7 Output grounds 5..8, slave unit when connected8 Output grounds 1..4, slave unit when connected

6 23 14578

Pinout of RJ45 Jack

Pinout of RJ45 Jack for MODBUS

Pin Signal1 Not Connected2 Not Connected3 Not Connected4 TXD1/D15 TXD0/D06 Not Connected7 +12..+24V DC8 Ground

F IMPORTANT: 4..20MA AND MODBUS VERSIONS ARE NOTINTERCHANGEABLE -- VERIFY YOUR CONFIGURATION BEFORECONNECTING GROUND MASTER!

Terminal Block Outputs(Ground Master RT)Ground Master RT enablesautomatic shutdown of the tools,provides signal to many types oftower alarm light, as well asprovides logic signal for use insimilar circumstances. Three ba-sic configurations are recom-mended: Dry Contact, 24VOutput and 5V Output (see to theright).

Dry relay contacts are closed whenGround Master is plugged in andall monitored grounds are withinacceptable limits. If any of thegrounds fails or if power toGround Master fails, contact willbecome open. If you connectinductive load, such as relay coil,to the relay contacts, a protectivediode must be utilized.

Logic level is CMOS and TTL com-patible. Output is normally zeroand becomes logic “1” when anyof the grounds fails.

GND +24V +5V

GND +24V +5V

GND +24V +5V

Dry Contact0..250V DC or AC,

100mA

24V output+24V

from thetool

+24Vfrom the

tool

+5VLogic

output

+24Vfrom the

tool

Dry Contact

+24V Output for Relay, etc.(100mA max.)

+5V Logic Levet Output

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