APC 6000 user manual Example of CRC computation

Page 15

JBUS protocol (continued)

Example of CRC computation

CRC register initialization									Shift 1	1111	1111	1111	1111
				of 1st character								0000	0010

										1111	1111	1111	1101
									Shift 1	0111	1111	1111	1110	1
Set flag to 1,								polynomial		1010	0000	0000	0001

										1101	1111	1111	1111
Set flag to 1,									Shift 2	0110	1111	1111	1111	1
Set flag to 1,								polynomial		1010			0001

										1100	1111	1111	1110
									Shift 3	0110	0111	1111	1111	0
Set flag to 0									Shift 4	0011	0011	1111	1111	1
										101			1

										1001	0011	1111	1110
									Shift 5	0100	1001	1111	1111	0
									Shift 6	0010	0100	1111	1111	1
										101			1

										1000	0100	1111	1110
									Shift 7	0100	0010	0111	1111	0
									Shift 8	0010	0001	0011	1111	1
										101			1

										1000	0001	0011	1110
				2nd character								0000	0111

										1000	0001	0011	1001
									Shift 1	0100	0000	1001	1101	1
										101			1

										1110	0000	1001	1101
									Shift 2	0111	0000	0100	1110	1
										101			1

										1101	0000	0100	1111
									Shift 3	0110	1000	0010	0111	1
										101			1

										1100	1000	0010	0110
									Shift 4	0110	0100	0001	0011	0
									Shift 5	0011	0010	0000	1001	1
										101			1

										1001	0010	0000	1000
									Shift 6	0100	1001	0000	0100	0
									Shift 7	0010	0100	1000	0010	0
									Shift 8	0001	0010	0100	0001	0
										byte		byte

6739389EN/FB - Page 15

Image 15

Contents GTC link communication interface Mgetm GalaxyTM2 6739389EN/FB Contents COM module PresentationIntroduction ACQ moduleInterface Communication settingsJbus protocol Principle Synchronizing data exchangesDescription of request and response frames Checking received messages on the slave side Function 1 and 2 read N bits FunctionsFunction 5 writing a bit Function 3 and 4 read N wordsFunction 6 writing a word Function 8 reading error diagnosis countersFunction 15 writing n consecutive bits Function 11 reading event countersMSB LSB MSB LSB MSB Function 16 writing n consecutive wordsCRC 16 algorithm Example of CRC computation Table of Most Significant Bytes for CRC16 Computation Example of CRC 16 computation in C using table lookupJbus protocol Unitary UPS UPS theory of operationParallel connected UPS with Static Switch cubicle Operation without batteryUPS without Mains Operation with battery Block diagram Unitary UPSMeasured quantities Normal operation Load on battery Main status bits UPS operating informationOperating modes Load on Mains Load on bypass Parallel connected UPS Main status bits of system operations Normal operation Load on battery DisconnectedStatic Switch cubicle Static Switch Main indicators of system operationsNormal operation Load on Mains Load on bypass Message format Example of read data array commands sent by the terminalSample commands List of variable fields System informationGeneral definitions Signaling field Tables of measured dataCurrent fields Voltage fields Power fields Frequency fieldsBattery and adjustments fields Tables of binary dataRectifier-charger Connectivity InverterGlobal information Table of control devicesWord address Glossary of information descriptorsInverter stack overload 0=no/1=overload Word address 4C Word address 4AWord address 4E summary Word address 4DWord address C1 C10 call reset 0= not activated / 1=activated

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