Red Lion GEMINI 42 - Manual (Page 10)

DIAGNOSTICS, SELF-TEST, & “WATCHDOG” TIMER [Cont’d]
Another error indicator is the “watchdog” timer. In order to insure the
software is functioning properly, the program constantly monitors itself. If the
proper sequence and timing of internal events does not occur, an “E” will appear
on the left side of the display. If this occurs, refer to the “Troubleshooting Guide”
for directions.
The final type of built-in error checking is the front panel initiated self-test. It
can be performed at any time, even when the Gemini is running. It will not
interfere with the accumulation of counts or control functions. A function code of
“6”, “+/-” starts the test. At this time, whatever was displayed will disappear and
be replaced by a string of decimal points and the overflow indicator. Then the
display will show a string of 9’s, then 8’s etc., until a string of 0’s are shown. The
self-test will then turn off the overflow indicator and activate the minus “-” sign.
Then the unit shows an interlace pattern of -010101, then -212121, followed by
232323 etc., until -898989 is reached. At this time the outputs can be tested by
pressing the “1” or “2” key. (The program disable terminal must be disconnected
in order to allow activation of the outputs. Also, when testing the output, use
caution, so as not to cause any undesirable or hazardous conditions in the
system.) An automatic exit will take place after six seconds or immediately if the
Program Disable terminal is connected to common. Normal length of display
time for each of the patterns is approximately 0.5 sec. Rapidly pressing “E”
during self-test can speed up the sequence.
INPUT CIRCUITRY & SET-UP
There are two independent input channels on the Gemini. Various types of
sensor outputs can be accommodated by appropriate DIP switch set-up. These
include: TTL or CMOS logic, current sinking, current sourcing, or dry contact
and more.
Channel 1 consists of a logic input and a separate low level magnetic pickup
input.
Channel 2 is a completely independent count or control input channel. Like
Channel 1, it can be programmed with DIP switches for a wide variety of logic
inputs, and is identical to Channel 1 in this regard. For a complete detailed
description of input set-up, see Appendix “A”.
OVERFLOW INDICATION
The Gemini features an overflow indicator (LED) which is located to the left
of the sixth digit and above the polarity annunciator. This LED will turn on if the
capacity of the display (6-digits) is exceeded or if the internal count capacity
(9-digits) is exceeded. Use of extremely small scale multiplier and Scale Factor
Values can cause the internal count capacity to overflow before the displayed
value would overflow. It should also be noted that the use of Right Hand Dummy
Zeros or Scale Factors larger than one could cause the displayed value to
overflow before a value of 999,999 (6-digits) is accumulated.
When the capacity of the display is exceeded, the count value will be
maintained and will be valid. But if the internal count value is exceeded, then this
value may no longer be valid.
The overflow LED can also turn on under certain conditions when the rate
input frequency exceeds the maximum 3250 cps allowed for a rate update period
of 16 sec. See Code 63 - “Rate Minimum Update Time”.
-8-