Robertson/CDL Survey Gyros

[Gina McLauchlan]

This is one carried over from the old forum

Hello,

I am working on an interface system to connect a CDL Mini RLG to MRV5, for controlling the autoheading function. MRV%’s topside computer has a port for heading data input from a Robertson Gyro.

To do this, I need to strip the heading data from the CDL output string. This is quite straightforward, I can do it using a BASIC Stamp Micro-controller, or by using NI LabVIEW software.

I need to know what format the Robertson Gyro string is in, so I can have my software/Stamp emulate this before feeding it into MRV%’s topside computer.

Any info gratefully received.

Carl.

[Gina McLauchlan]

This is one carried over from the old forum

Hi Carl

The info below may be of some help.
It looks to me that the heading is the first, in the format of: H123.45 followed by Pitch, Roll, etc. etc.

DATA OUTPUTS for CDL MiniRLG

Data output strings available from DDU

MiniRLG1
H123.45P+12.345R+123.456M123W1234.56U12.3<CR><LF>

MiniRLG2
H12345P+12345R123456M123W123456U123<CR><LF>

MDL
H1234P+1234R+1234<CR><LF>

SGB
1234<CR><LF> (heading)

Legend:
H Heading
P Pitch
R Roll
M Mode 1st digit 0 = Idle
1 = Coarse stationary align
2 = Fine stationary align not complete
3 = Fine stationary align complete
9 = Aided navigation
A = System failure
Mode last byte is the navigation monitor byte in hex
W Depth
U Battery voltage

DLOG
H1234P+1234R+1234E<CR><LF>
Final flag character is either:
E Exact heading available
S Gyro settling

SKR
4 characters (most significant first)

UART encoded with address encoding in bits 4 and 5 and BCD digit in bits 0-3
Bits 6 and 7 always zero
00110011=Hundreds digit 3
00100101=Tens digit 5
00010111=Units digit 7
00000010=Tenths digit 2
Heading 357.2 degrees

best regards
James Mc

[Gina McLauchlan]

This is one carried over from the old forum

I’ve looked at the CDL manual on their website, it is possible to get the CDL to output a data string which is in Robertsons format ($xxx.xx where xxx.xx is the heading)

So, all we have to do is set it up to output that and Bobs your Auntie.

Of course, the gyro they’ve sent us ‘aint even calibrated so its really all gonna be a waste of time!

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