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LabVIEW drivers - Endress-Hauser Minilog-B


Endress-Hauser Minilog-B

If the ReadWin program provided by Endress-Hauser does not satisfy your needs, here is a straightforward vi that allows you to read from the Endress-Hauser Minilog-B datalogger and store the data with a samplerate higher than 1 sample per minute. The maximum samplerate is about 60 samples per minute or 1 sample per second.

There is a small additional vi that will perform the necessary checksum calculations.

Transferprotocol

In this sample a MiniLog-B datalogger is connected to a PC using a RS232 serial interface.
The settings for the connection are: Baudrate - 4800, Databits - 1, Stopbits - 0, Parity - None.

The PC requests the datalogger for a readout with the following sequence of characters:

	C H A R A C T E R
	nr  ASCII  hex  remark
	 1  [SOH]  01
	 2  0      30
	 3  1      31
	 4  [STX]  02
	 5  R      52
	 6  0      30
	 7  1      31
	 8  0      30
	 9  [ETX]  03
	10  '      60   checksum

The datalogger responds with:

	C H A R A C T E R
	nr  ASCII  hex  remark
	 1  [SOH]  01
	 2  0      30
	 3  1      31
	 4  [STX]  02
	 5  0      30
	 6  +      2B
	 7  0      30
	 8  0      30
	 9  ,      2C
	10  0      30
	11  0      30
	12  [ETX]  03
	13  4      34   checksum

Checksum calculation

The checksum can be calculated by xor-ing an initial value (0, zero) with all values after and before .
Here is the checksum calculation for the abovementioned request for a readout:

	C H A R A C T E R      C H E C K S U M
	ASCII hex bin          bin        hex
	                       0000 0000  00
	0     30  0011 0000    0011 0000  30
	1     31  0011 0001    0000 0001  01
	[STX] 02  0000 0010    0000 0011  03
	R     52  0101 0010    0101 0001  51
	0     30  0011 0000    0110 0001  61
	1     31  0011 0001    0101 0000  50
	0     30  0011 0000    0110 0000  60

Special ASCII codes

The abovementioned communication strings contain so called communication control characters. Here's an explanation of the used codes:

	C H A R A C T E R
	ASCII  explanation
	[SOH] start of header
	[STX] start of text
	[ETX] end of text

Downloads

logger.ini
Support file (initialisation).

crc.vi
This sub vi calulates the checksum used in the communication protocol.

vi-endress-hauser-readout.vi
This sub vi reads one data point from the Minilog-B.

vi-endress-hauser.vi
This vi can be used as a datalogger.


Bart Boshuizen, 2004/01/18

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