Cdios controller commands 

All CDIOS messages are presented as 8 bytes long. When variable length messages are selected, the part of the message that is not send over the CAN bus is represented in italic/lightgray text.

This command reads/writes A/D converter and calibration values.
 

Command	Module ID	3	4	5	6	7	8
2Fh	0 - 15	Selector	Data or zero (lsb)         (msb)		0	0	0

Parameter	Value	Description	Data in Command	Data in Reply
Selector	00h 01h 02h 03h	Read Offset calibration value of input #1 Write Offset calibration value of input #1 Read Gain calibration value of  input #1 Write Gain calibration value of  input #1	- X - X	X - X -
	10h 11h 12h 13h	Read Offset calibration value of input #2 Write Offset calibration value of input #2 Read Gain calibration value of  input #2 Write Gain calibration value of  input #2	- X - X	X - X -
	20h 21h 22h 23h	Read Offset calibration value of input #3 Write Offset calibration value of input #3 Read Gain calibration value of  input #3 Write Gain calibration value of  input #3	- X - X	X - X -
	FDh	Stop calibration measurements. After this, the 6162  has to be re-initialized because sample rate, number of channels and filter settings may have changed.	-	-
	FEh	Setup for calibration measurements: Basic sample rate set for 60 Hz suppression. Measured channels set to 3. Offsets set to zero. Gains set to one. Filters set to maximum. Ohm to temperature conversion disabled 4 wire measurement	-	-
	FFh	Same as FEh, but set for 50Hz suppression	-	-

Normal reply is:

 

Reply	Module ID	3	4	5	6	7	8
2Fh	0 - 15	Selector (copy of command)	Data or zero (lsb)        (msb)		0	0	0

 Possible error message:

 

Error	Module ID	3	4	5	6	7	8
AFh	0 - 15	0	0	Error Status	0	0	0

Parameter	Bit	Description
Error status	0 1 2	1 = Selector parameter out of range 1 = Calibration value write sequence error (data ignored) 1 = FLASH EPROM programming failed

 

1. If not all 6 calibration factors are to be adjusted; first read the calibration values that are to be left unchanged and store them in the calibration table (because ALL values have to be written....).
   
2. Initialize the A/D converter with command 2Fh, Selector code FEh or FFh, to measure 3 channels with 50 or 60Hz suppression, maximum filter setting and Ohm to temperature conversion disabled.
   
3. Connect 3 special 'zero Ohm' resistors to the input connectors.
   
4. For every input to be calibrated:
   • Wait 2 seconds for the input filters to stabilize
   • Read value with a 'Read analog inputs' command (28h).
   • Store the Input value as Offset value in the calibration table.
     
5. Connect 3 exactly known precision resistor of approx. 360 Ohms to the input connectors.
   
6. For every  input to be calibrated:
   • Wait 2 seconds for the input filters to stabilize.
   • Read value with a 'Read analog inputs' command (28h), this value is UNSIGNED
   • Calculate new 16 bits Gain value, so that a 400 Ohms input will generate 60000 as A/D value.
     Calculation should be done with at least single precision floating point arithmetic, rounded to unsigned integer.
     
     Gain value =   Input Ohms * 150 / (Input value - Offset value) *  10000h
     
     Gain value =  Input Ohms / (Input value - Offset value) *  9830400
     
     This gain value should not be higher then 64435 (0FFFFh).
     
     Store this Gain value in the calibration table.
     
7. Write all 6 calibration values from the table to the 6162:
   • Writing must be done in ascending order (command 2Fh, Selector codes: 01h, 03h, 11h, 13h,  21h and 23h), otherwise the 6162 will return the 'Calibration value write sequence error'.
     The data is internally buffered by the 6162 in RAM.
     
   • There must be an maximum delay of 100 mS between two write commands, otherwise the next calibration write command will return the 'Calibration value write sequence error'.
     
   • After the last write command (2Fh, Selector code 35h), the 6162 erases the calibration FLASH EPROM and writes the new values. This can take up to 500 milli-seconds before the 6162 sends a reply or error message.
     
8. Send the 'Reset 6162' Command (2Fh, Selector code FDh) to resume normal operation