Campbell Scientific CR10 CR10 Measurement and Control - Page 213

APPENDIX C. BINARY TELECOMMUNICATIONS each Representing the bits in the first byte of most two byte pair as ABCD EFGH (A is the are significant bit, MSB), the byte pairs described here. LO RESOLUTION FORMAT - D,E,F, NOTALLONES BitsDescriptionl0XX.XX A Polarity,0=+, 1=-. B, C Decimal locators as defined below. D-H plus 13 bit binary value (D=MSB). second Largest possible number without D, E, and F all 1 is 7167, byte but CSI defines the largest allowable range as 6999. The decimal locators can be viewed as a negative base 10 exponent with decimal locations as follows: B C nO On O 1 Decimal Location XvXvvXvX' XXX.X 1 1 X'XXX DATA TypE WHEN D,E,F, ALL E.UAL ONE lf D, E, and F are all ones, the data type is determined by the other bits as shown below. X implies a "don't care" condition; i.e., the bit can be either 1 or 0 and is not used in the decode decision. A B C D E F G H DATATYPEANDSECONDBYTEFORMAT 1 1 1 1 1 1 XX XX 0 1 1 1 XX 00 1 1 1 1 XX 01 1 1 1 1 11 A,B,C,=1-StartofOutputArray,G&Harethemost significant bits of the Output Array lD. All 8 bits of the 2nd byte are also included in the lD. C=0-Firstbyteofa4bytevalue. A,B=0;C=1-Thirdbyteofa4bytevalue. A=0; remainingbits=1-Firstbyteofa2byte "dummy" word. The CR10 always transmits a 0 for the 2nd byte, but the word can be decoded on the basis of the 1st byte only. HI RESOLUTION FORMAT Continuing to use the A-H bit representation, the four byte number is shown below as two two byte pairs. ABO111GH XXXXXXXX OO1111GH XXXXXXXX B|TS, 1ST BYTE, 1ST PAIR CDEF=0111 B G,H,A, 2nd byte ABCDEF = 001111 G H 2nd bvte DESCRIPTION Code designating 1st byte pair of four byte number. Polarity,0=*, 1=-. Decimal locator as defined below. 16th - gth bit (left to right) of 17 bit binary value. Code designating 2nd byte pair of four byte number. Unused bit. 17th and MSB of 17 bit binary value. 8th - 1st bit (left to right) of 17 bit binary value. c-3