B875-102 High Speed Analog Input, Communications with the PLC

Input Ranges and Output Data Limits

As shown in the following table, data can be in either raw binary or converted binary format. Within the 2% maximum over-range margin allowed, no error code is reported to the PLC.

Input Ranges and Output Data limits

Voltage range	Input Voltage	Raw Binary	Converted Binary
0—5 V	0.000	0000	0000
	5.000	4096	5000
	5.127 (max)	4200	5127
1—5 V	1.000	0000	1000
	5.000	4096	5000
	5.127 (max)	4200	5102
0—10 V	0.000	0000	0000
	9.999	4095	9999
	10.000	4096	N/A
	10.254 (max)	4200	N/A
-5—+5 V	-5.000	0000	Disallowed
	0.0000	2048	N/A
	5.000	4096	N/A
	5.254 (max)	4200	N/A
-10—+10 V	-10.000	0000	Disallowed
	0.000	2048	N/A
	10.000	4096	N/A
	10.508 (max)	4200	N/A

Diagnostic Communications

Diagnostic procedures are executed during the five second initialization period following power--up. Diagnostic routines are also run during wait states concurrent with executing A/D conversions. System diagnostics are: RAM checks, ROM checks, UART checks, as well as checking the legality of configuration switch settings and monitoring the ability to autocalibrate.

If the module fails to pass an internal diagnostic, two retries are made. If either one succeeds, the temporary lack of diagnostic is not reported to the PLC but the module system continues processing uninterrupted. If the module fails the diagnostic three times, the system goes into a power--up reset condition. switch settings and monitor

NOTE: While power-up diagnostics are running, or following detection of a hard failure, data is not available to the PLC.

Good Data. The following illustration shows status flags and data word format for good data to the PLC. When sending good data, status flag bits 14 and 15 are reset to 0.

Good Data Word Output to PLC

Out-of-range Data. The following figure shows status flags and data word format of out-of-range data output to the PLC. When sending out-of-range data, status bit 14 will be reset to 0, bit 15 will be reset to 1, and the out-of-range indicator will illuminate.

Out-of-range Data Word Output to PLC

Out--of--Range requires careful examination. Since the module receives instantaneous data from the field but sends averaged data to the PLC, instantaneous data less than 0 or greater than 4200 in RB format is considered out-of-range. Such data will be forced (clamped) to 0000 for under--range and 4200 for over-range values. However, the averaged data will not necessarily be out-of-range if the condition existed for less time than the total averaging period.

In this case, the format indicates at least one of the instantaneous data samples in the average is out of range. Its value for averaging purposes is the clamped value; the average may or may not be out of range. The red out-of-range light will remain on as long as an out-of-range data sample is included in the average.