Hiprom Technologies 1756HP-GPS User Manual

1756HP-GPS

USER MANUAL

Rev 2.8 – March 2009

1756HP-GPS - User Manual Rev 2.8

Table of Contents

Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8

Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F

Introduction ......................................................................................................3

Module Accessories .........................................................................................4

Module Operation.............................................................................................5

Installing the Module ........................................................................................7

Configuring the Module ....................................................................................8

I/O Address Map ............................................................................................12

Module Specific Commands ..........................................................................17

Module Status ................................................................................................23

PLC Ladder Example.....................................................................................26

Recommended PLC Data Types ...................................................................27

Specifications .................................................................................................31

GPS Operation...............................................................................................32

Time standards ..............................................................................................36

Glossary .........................................................................................................38

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CHAPTER 1

INTRODUCTION

The 1756HP-GPS module provides accurate time and position information and services
for the Allen-Bradley ControlLogix PLC system.

The module makes use of Global Positioning System (GPS) technology to derive accurate
time which is synchronized with the atomic clocks located on the GPS satellites.

This document serves to describe the functionality, installation, configuration and use of
the module.

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CHAPTER 2

MODULE ACCESSORIES

Each 1756HP-GPS package includes the following components:

• 1756HP-GPS module

• 5m RG58 patch lead with a SMA male and TNC male connector on either end

• 3.3V active 50Ω hard mount antenna

• 1756HP-GPS user manual

HIPROM GPS

LOCK

PPS LOC OK

Figure 2.1 : 1756HP-GPS module with antenna and patch-lead

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CHAPTER 3

MODULE OPERATION

The 1756HP-GPS module is designed to operate within the Allen-Bradley ControlLogix
PLC system. All power required for the module’s operation is derived from the 1756
backplane.

Alphanumeric Display

Status LEDs

Reserved External Interface Port

SMA Antenna Port

Figure 3.1 : 1756HP-GPS Layout

The on-board GPS receiver is connected via the external SMA antenna port and external
antenna patch-lead to the active GPS antenna. As soon as the module is powered-up it
will begin searching for available GPS satellites. Soon after lock on at least 4 satellites has
been achieved the module’s internal time will become valid.

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The current status of the module is conveyed to the user by means of the 3 bi-color Status
LED’s and the alphanumeric LED display.

The following information is available to the user directly across the backplane by means
of a scheduled connection:

• Date and Time in Gregorian Format (year, month, day, hour, minute etc.)

• Universal Coordinate Time (UTC)

• GPS Receiver Status

• Number of satellites being tracking

• Position in Polar Coordinates (latitude, longitude and altitude)

• Position in Cartesian Coordinates ( Earth-centered-earth-fixed X,Y,Z axis)

• Velocity in Polar Coordinates (Northerly, Easterly and Upward)

• Velocity in Cartesian Coordinates ( Earth-centered-earth-fixed X,Y,Z axis)

The module requires regular updates of the ControlLogix Controller’s CST (Coordinate
System Time) value to enable accurate CST conversion and wall-clock offset functions.

All time and date information can be adjusted to the local time-zone by configuring the
Time-Zone offset, in the scheduled output image.

Detailed GPS satellite information can also be requested by means of an unconnected
message, responding with the following for each of the 8 GPS receiver channels :

• Satellite Identifier (PRN)

• Current Satellite Azimuth

• Current Satellite Elevation

• Signal Strength

The 1756HP-GPS module supports two unconnected time conversion services, namely:

• CST Æ UTC and Gregorian

• UTC Æ Gregorian

This allows the user by means of a custom message service to convert between different
time formats. The conversion is valid only for time data that is less than 1 hour old.

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CHAPTER 4

INSTALLING THE MODULE

GPS utilizes a spread spectrum signal in the 1.5GHz range, and thus cannot penetrate
conductive or opaque surfaces. Thus the antenna should be mounted in a horizontal
position with an unobstructed view of the sky.

Attach the antenna patch lead to the antenna. It is recommended that waterproofing tape
be used to seal the connection.

NOTE: Should a longer patch lead be required it is recommended that a GPS signal

booster is used. Contact your local Hiprom distributor for assistance.

The module is equipped with a RIUP (Removal and Insertion Under Power) circuitry
enabling the module to be installed or removed from the chassis while power is applied.

Attach the patch lead SMA (male) to the module’s SMA (female) connector. It is not
recommended that the antenna patch lead exceed a total loss of 10dB at 1.5GHz, as this
may increase the time to GPS lock, or in extreme cases, prevent GPS lock from being
achieved at all.

Once the module has been powered up for the first time, it will search for satellites from a
cold start (i.e. no almanac). The module will take approximately 5 minutes to acquire Lock.
Once a complete almanac has been downloaded, the time to achieve fix will be reduced to
around 45 seconds.

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CHAPTER 5

CONFIGURING THE MODULE

A direct connection between the controller and the 1756HP-GPS module is required to
transfer I/O data to and from the module. In addition the module supports various
unconnected messages that can be used to retrieve particular information.

5.1. Establishing the Direct Connection

This section describes the procedures necessary to configure the 1756HP-GPS module
within the ControlLogix system. Each 1756HP-GPS module must be owned by a single
ControlLogix controller.

The 1756 Generic Module is used in RSLogix5000 to configure the module. The
configuration of the module is detailed in the table below.

Data Format

CommFormat Data – DINT

Connection parameters
Description Instance Size
Input 1 29
Output 2 3
Configuration 4 2

RPI

Min 1.0 msec Max 750.0 msec

Table 5.1 : 1756HP-GPS connection parameters.

The steps required to add a new 1756HP-GPS module are detailed below.

Figure 5.1 : Right-click on I/O Configuration and select New Module

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Figure 5.2 : Select Generic 1756 Module ( 1756-MODULE )

Figure 5.3 : Configure module’s parameters

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Figure 5.4 : Configure module’s RPI (Requested Packet Interval)

Ensure that the first configuration byte of the configuration image is set to 0x00, as
illustrated below. If the user is using RSLogix 5000 v16 the UTC time base is different from
previous versions of RSLogix. To ensure that ControlLogix PLC’s running different
versions can be time synced using the 1756HP-GPS module the user must select if v16 is
used or not. The last bit (least significant bit) of the second byte of the configuration image
configures the module to use or not use v16 UTC time. By setting the bit, the module will
use v16 UTC time. The highest bit (most significant bit) of the second byte of the
configuration image configures the module to be the CST master. By setting this bit, the
module will attempt to become the CST master. If a CST master is present, it will not
become the CST master and indicate that a duplicate master was detected.

Configuration Image

BYTE VALUE

0
1

0x00
0x??

Byte 1 = X000 000Y (binary) where ‘X’ will make the module a CST master if set to 1 and
‘Y’ will make the module use v16 UTC time if set to 1.

Once a modules configuration data has been downloaded to the controller, it will attempt
to establish a connection with the module. A connection will fail if there is inappropriate
configuration data.

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5.2. Coordinate System Time Master

It is important that at least one controller or 1756HP-GPS module in the ControlLogix rack
be configured as the Coordinate System Time master. This can be configured in
RSLogix5000 by right-clicking on the Controller and selecting Properties. Ensure that the
checkbox as indicated below is checked to make the controller the CST master; otherwise
the procedure in section 5.1 above may be followed to make the 1756HP-GPS module the
CST master.

Figure 5.5 : Configure CST Master

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CHAPTER 6

I/O ADDRESS MAP

The input and output image of the 1756HP-GPS module is defined in the following
sections. Appendix A and B provide example code and recommended structures that can
be used to extract and view the data.

6.1. Input Image

Figure 6.1 : Connected Input Image

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