Digi RCM4000 - Manual (Page 55)

User’s Manual 49
Reads the voltage of an analog input channel by serial-clocking an 8-bit command to the A/D converter
by its Direct Mode method. This function assumes that Mode1 (most significant byte first) and the A/D
converter oscillator have been enabled. See anaInConfig() for the setup.
The conversion begins immediately after the last data bit has been transferred. An exception error will
occur if Direct Mode bit D7 is not set.
PARAMETERS
cmd contains a gain code and a channel code as follows.
D7—1; D6–D4—Gain Code; D3–D0—Channel Code
Use the following calculation and the tables below to determine cmd:
cmd = 0x80 | (gain_code*16) + channel_code
len , the output bit length, is always 12 for 11-bit conversions
unsigned int anaInDriver(unsigned int cmd,
unsigned int len);
Gain Code Multiplier
0 Ч1
1 Ч2
2 Ч4
3 Ч5
4 Ч8
5 Ч10
6 Ч16
7 Ч20
Channel Code
Differential Input
Lines
Channel Code
Single-Ended
Input Lines
*
* Negative input is ground.
4–20 mA
Lines
0 +AIN0 -AIN1 8 AIN0 AIN0*
1 +AIN2 -AIN3 9 AIN1 AIN1*
2 +AIN4 -AIN5 10 AIN2 AIN2*
3
†
† Not accessible on Prototyping Board
+AIN6 -AIN7 11 AIN3 AIN3
4 -AIN0 +AIN1 12 AIN4 AIN4
5 -AIN2 +AIN3 13 AIN5 AIN5
6 -AIN4 +AIN5 14 AIN6 AIN6
7
‡
‡ Not accessible on Prototyping Board
-AIN6 +AIN7 15 AIN7 AIN7*