Datasheet
• Positional accuracy (CEP50) autonomous positional error less than 2.5 meters
• SiRF Star IV GPS chip
• Satellite-based augmentation systems: WAAS, EGNOS, MSAS, GAGAN
• High sensitivity navigation engine (PVT) tracks as low as –163 dBm
• Modbus slave device; RS-485 half-duplex serial communications
• Internal GPS updates once every second
• Environmental rating: IP69K per DIN 40050
• Operating temperature of −40 °C to +80 °C (−40 °F to +176 °F)
• Available with a 2 meter integral cable with flying leads
Model
Power
Requirements
Features
GPS50M 5 to 30 V dc
Modbus protocol on RS-485 serial.
Latitude, longitude, altitude (meters), time, and date in
signed integer and floating point formats
Modbus Registers for the GPS Module
The GPS module only responds to 16-bit Modbus holding register commands. Most GPS data fields require two 16-bit
registers to access the entire data value. These 32-bit values are stored as signed integers or floating point values. By
default, the Modbus Slave ID is set to 1.
The GPS device may take a few minutes to achieve a satellite fix, depending on the signal quality and environment.
GPS Location Registers
The Banner GPS unit uses 10 Modbus registers to store the GPS readings for latitude, longitude, altitude (in meters), date,
and time. Read the data from the GPS using one of two formats: 32-bit signed integer or 32-bit floating point. Because
Modbus registers are only 16-bits per register, two registers are used for every GPS value. Modbus registers 1 through 10
contain the 32-bit signed integer value. Modbus registers 101 through 110 contain the 32-bit floating point value.
GPS Modbus Registers
Definition DescriptionSigned Floating Point
Upper Lower Upper Lower
1 2 101 102 Latitude
0 to ±90°
From the equator north(+) or south(–) position of a point on
the Earth's surface. Integer value is fixed at 7 decimal points
3 4 103 104 Longitude
0 to ±180°
From the Prime Meridian east(+) or west(–) position of a point
on the Earth's surface. Integer value is fixed at 7 decimal
points
5 6 105 106 Altitude
Calculated altitude above sea level in meters(±). Integer value
is fixed at 5 decimal points.
7 8 107 108 UTC Time HHMMSS (Hour, Minute, Second) of UTC time
9 10 109 110 Date DDMMYY (Day, Month, Year)
GPS Module
Original Document
178135 Rev. C
20 February 2015
178135
GPS Satellite Registers
The GPS accuracy is based on the number of satellites tracked, their positions and whether DGPS (Differential Global
Positioning System) is available for use. The Signal Quality register defines if the receiver has achieved DGPS (WAAS for
North America), GPS fix or no fix. A DGPS fix is the most accurate.
The DOP (Dilution of Precision) registers help quantify the quality of the fix the receiver has achieved.
Modbus
Register
Description Value Definition
2005–2006 Signal Quality 0 Invalid
1 GPS fix
2 DGPS fix
2007–2008 Number of Satellites Being Tracked 1 through 12
Satellite PRN, elevation, azimuth, and
signal strength is saved in the satellite data
table.
2009–2010 Time (in seconds) Since the Last DGPS Update
2D/3D Fix Registers
Modbus registers 2103 and 2104 (ASCII) contain a decimal code in ASCII that defines the level of satellite fix.
Modbus
Register
Description Value Definition
2103–2104 2D/3D Fix
1 (ASCII 49) No fix
2 (ASCII 50) 3 satellites
3 (ASCII 51) 4 or more satellites
PDOP - Positional Dilution of Precision Registers
The Positional Dilution of Precision is a result of the HDOP and VDOP where PDOP
2
= HDOP
2
+ VDOP
2
.
Generally, the more satellites used in the solution, the smaller the DOP values, which result in smaller solution error.
Larger Dilution of Precision values occur when the set of satellites used in the position fix are not spatially diverse (spread
out across the sky) from each other. This error can be mitigated by placement of the module and its antenna such that it
has clear view of as much of the sky as possible.
Modbus
Register
Description Value Definition
2129–2130 Positional Dilution of Precision 0.0 to 14.4
The smaller the number, the more accurate
the readings.
HDOP - Horizontal Dilution of Precision Registers
This number represents the horizontal component of the dilution of precision. This is a geometric factor that, when
multiplied by measurement and other input error, gives the error in position.
Modbus
Register
Description Value Definition
2131–2132 Horizontal Dilution of Precision 0.0 to 10.2
The smaller the number, the more accurate
the readings.
VDOP - Vertical Dilution of Precision Registers
This number represents the vertical component of the dilution of precision. This is a geometric factor that, when multiplied
by measurement and other input error, gives the error in position.
GPS Module
2 www.bannerengineering.com - Tel: +1-763-544-3164 P/N 178135 Rev. C