Measurement Computing Data Translation DT9857, User Manual

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Appendix C
182
Writing to the EEPROM Register
If you want to change the default values for the coupling type, current source, and Sync Bus
termination that are defined in the Open Layers Control Panel programmatically, you can use
the Data Acq SDK function
olDiagWriteReg to write to the EEPROM register of each DT9857
ad DT9857E module.
The Open Layers Control Panel has controls for setting the following parameters, which are
stored in 8 consecutive bytes of EEPROM:
• Coupling type. The values COUPLING_TYPE_AC or COUPLING_TYPE_DC are stored
as constants for these controls.
• Current source. The values EXCITATION_CURRENT_SRC_INTERNAL or
EXCITATION_CURRENT_SRC_DISABLED are stored as constants for these controls.
• Sync Bus termination (supported on the DT9857E module only). The value is 0x01.
These controls may also be “uninitialized” if, for some reason, the DT9857 or DT9857E module
skipped the post-manufacturing initialization process.
To access the storage locations programmatically, use the olDiagReadReg() and
olDiagWriteReg() functions. The following code shows the location of these controls in the
register map:
#define I2C_MEM_BASE 0x00000000
// Coupling storage offsets relative to the base address for the
// analog input channels
#define EEPROM_OFFSET_COUPLING 0x0020
#define EEPROM_OFFSET_COUPLING_END 0x002F
// Current source storage offsets relative to the base address for
// the analog input channels
#define EEPROM_OFFSET_CURRENT_SOURCE 0x0040
#define EEPROM_OFFSET_CURRENT_SOURCE_END 0x004F
//Sync Bus termination offset from the base address
#define EEPROM_OFFSET_SYNC_TERMINATION 0x0C490
To update the coupling type, use the olDiagWriteReg() command as follows:
OLSTATUS olStatus = olDiagWriteReg(m_hDev, I2C_ME
EEPROM_OFFSET_CO channelNumber, couplingType, 1);
To read the coupling type, use the olDiagReadReg() command as follows:
OLSTATUS olStatus = olDiagReadReg(m_hDev, I2C_ME
EEPROM_OFFSET_CO channelNumber, couplingType, 1);
To update the current source, use the olDiagWriteReg() command as follows:
OLSTATUS olStatus = olDiagWriteReg(m_hDev, I2C_ME
EEPROM_OFFSET_CURRENT_ channelNumber, currentSource, 1);