3.3 CJC Output
The OME-DB-889D provides Cold-Junction Compensation (CJC) for the thermocouple applications. If the CJC is required, place the JP17 in the position of the channel to be used as a CJC reference. If the CJC is not required, Place the JP17 in the position “X”.
CJC has output on connector CN7. Using a voltage meter measures CN7 which exists a voltage related to the OME-DB-889D board temperature. The CJC voltage transfers to temperature with formula:
T(°C) = V*1000/24.4
CN7
Voltage meter
A.GND
V: Voltage of CN7
T: Temperature of OME-DB-889D
Example: (Turbo C)
Multi-Function Card: OME-A-822PGL The OME-DB-889D JP17 placed on “7”.
/*====================Example Program ===================*/
#include <stdio.h> #include “A822.h>
main(void)
{int ad_channel , gain , trigger_mode, poll_data ; float temp;
A822_Initialize(0,0x220, -1, -1);
/* Initials OME-A-822PGL Ref. OME-A-822PGH/L Software Manual */
ad_channel=7; gain=0; trigger_mode=1;
for(;;)
{
A822_AD_SetChGainMode(ad_channel , gain , trigger_mode );
/* SettingOME-A-822 A/D channel =7 , Gain=1 , Trigger mode = Software trigger */
poll_data=A822_AD_PollingVar(); temp=(float)(((poll_data-2048)*5/2048)*1000/24.4); prinf(“ Temperature = %4.1f °C \n”, temp);
}
}
OME-DB-889D User’s Manual | 14 |
