YSI 6200 - Manual (Page 99)

YSI 6200 DAS USER Manual
YSI/Massachusetts 508.748.0366, Fax 508.748.2543 Page 9-7
Checking Bit Alarms
The 6200 DCP records BIT flags as a parameter in the internal sensors file. You can use
EcoWatch DCP to view these flags by opening the internal sensors file (with the i in the 6
th
position) then selecting Setup:Parameters:Add/Remove and selecting BIT Alarm.
Alarm processes
Many of the alarm processes have both process outputs (a status value of 1 or 0) and digital
outputs (high or low). The precise timing of when these outputs are set high (1) or low (0)
differs slightly.
Except where otherwise stated, digital outputs are set high or low immediately as the process
inputs enter or leave the alarm state; and only when the process inputs enter or leave the alarm
state. Thus, if the alarm reset process (or any other process) is used to set a high digital output to
the low state, it will not go high again until the alarm state is left and re-entered.
The numerical process output (0 or 1) is set to 1 the first time that the process is called with the
inputs in the alarm state. The process output remains at 1 until the end of the sample interval
time. This means that if the alarm is set and the re-set within a sample interval time, the process
output will be 0 until the alarm is first set; 1 from that point until the end of the sample interval;
and 0 from the start of the next sample interval. The reason for this is that the output message
will always notify the user that an alarm has occurred within the sample interval.
1 Built-In-Test (BIT)
Inputs none
Outputs 1 The bit-weighted result of all bit flags set by ZENO
®
-3200
internal procedures or by special user processes. The output
is formatted and printed as a hexadecimal value.
Various system functions or user processes are used to set bit flags in a global BIT value. Up to
31 bits can be assigned in the global BIT value (the 32nd bit is used internally by the ZENO, and
is not accessible to the user). This process reads and then clears the global BIT value.
The BIT Alarms can be interpreted as follows: The Hex column refers to the last two digits of
the BIT Alarm.
Flag # Binary Hex Description
1 00000001 01 System reset.
2 00000010 02 Real-time clock suspect.
3 00000100 04 Data logging memory initialized.
4 00001000 08 Serial device communication failure.
5 00010000 10 EEPROM suspect.
6 00100000 20 18-bit analog to digital converter suspect.
7 01000000 40 12-bit analog to digital converter suspect.
8 10000000 80 Clock adjustment made due to temperature compensation.
All of the above bit flags are logically ANDed together. For example, whenever the system
resets the BIT Alarm will be 01. If a serial devise like a sonde is disconnected when it is
supposed to be there the BIT Alarm will be an 08. If the system is reset and there is a serial
device error then the BIT Alarm will be 09 (01+08). If the 18-bit A-to-D converter is suspect and
the system resets, you would get a 21 (20+01).