Allen-Bradley MicroLogix 1200 Reference Manual page 28

1-12 I/O Configuration
Publication 1762-RM001C-EN-P
Specialty I/O Configuration
1769-IT6 Thermocouple Module Input Data File
The input data file contains the analog values of the inputs.
Bit Position
15 14 13 12
0 Analog Input Data Channel 0
1 Analog Input Data Channel 1
2 Analog Input Data Channel 2
3 Analog Input Data Channel 3
4 Analog Input Data Channel 4
5 Analog Input Data Channel 5
6 OC7 OC6 OC5 OC4 OC3 OC2 OC1 OC0 S7
7 U0 O0 U1 U0 U2 O2 U3 O3 U4 O4 U5 O5 U6 O6 U7 O7
The bits are defined as follows:
• Sx = General status bit for channels 0 through 5 and CJC sensors (S6
and S7). This bit is set (1) when an error (over-range, under-range,
open-circuit, or input data not valid) exists for that channel. An input
data not valid condition is determined by the user program. This
condition occurs when the first analog-to-digital conversion is still in
progress, after a new configuration has been sent to the module.
• OCx = Open circuit detection bits indicate an open input circuit on
channels 0 through 5 (OC0 through OC5) and on CJC sensors CJC0
(OC6) and CJC1 (OC7). The bit is set (1) when an open-circuit
condition exists.
• Ux = Under-range flag bits for channels 0 through 5 and the CJC
sensors (U6 and U7). For thermocouple inputs, the under-range bit is
set when a temperature measurement is below the normal operating
range for a given thermocouple type. For millivolt inputs, the
under-range bit indicates a voltage that is below the normal operating
range. These bits can be used in the control program for error
detection.
• Ox = Over-range flag bits for channels 0 through 5 and the CRC
sensors (O6 and O7). For thermocouple inputs, the over-range bit is
set when a temperature measurement is above the normal operating
range for a given thermocouple type. For millivolt inputs, the
over-range bit indicates a voltage that is above the normal operating
range. These bits can be used in the control program for error
detection.
11 10 9 8 7 6
S6
5 4 3 2 1 0
S5 S4 S3 S2 S1 S0