Sensoray 7429 - Manual (Page 22)

Set Alarm Limits
This command declares upper and lower alarm limits for the specified channel. After
declaring limits, an alarm will "sound" if sensor data for that channel strays outside of
the range defined by the alarm limits.
For example, if a temperature sensor is being used to monitor the temperature of a milk
storage tank, the upper alarm limit for that channel could be set to the highest "safe"
temperature for the tank. If this "safe" limit is exceeded, the 7429 would notify the host
so that appropriate action can be taken. This relieves the host of the burdensome task
of reading the sensor temperature and comparing it to the limit value.
If limits are not specified for a channel the low limit defaults to -32768 and the high
limit defaults to 32767.
Alarm limits may be changed via this command at any time. If only a lower limit is to
be used, specify an upper alarm limit value of 32767. Similarly, specify a lower limit
value of -32768 to use only an upper limit.
COMMAND: (32 + CHAN),
(HIGH LIMIT MSB),(HIGH LIMIT LSB),
(LOW LIMIT MSB),(LOW LIMIT LSB)
RESPONSE: NONE
Example: Channel 7 is connected to a type K thermocouple which is monitoring a
process temperature. The temperature must not fall below 400°C.
For this example, assume that the upper temperature limit is of no concern. The
7429 scales K thermocouple to 0.1°C/bit, so the low limit value must also be scaled
by the same factor. The upper limit is set to 32767 to disable the high alarm. The
code segment is:
CALL SendByte (32 + 7)'command + opcode
CALL SendWord (32767)'high limit
CALL SendWord (400 / .1)'low limit