
Chromalox Instruments and Controls
A-51643 Rev. 6 10/06/03 17
COMMUNICATIONS ACCESS CODE
LEVEL 1 PASSWORD (write not allowed while in setup mode)
LEVEL 2 PASSWORD (write not allowed while in setup mode)
4.5 Monitoring and Acknowledgement of Alarms, Events, and Cycle Complete, Discrete
Inputs, and Discrete Outputs
Two input registers allow monitoring of the alarm ($0094) and event ($0095) functions associated with
relay outputs 1-4. The corresponding input register represents a binary pattern that indicates the state of
each function. Bits 0-3 of the holding register value represent item 1-4 respectively. A bit value of 0
indicates off, while a bit value of 1 indicates on. Example: A read of holding register $0098 returns a
value of $0006. This would indicate that alarms 2 and 3 are active.
The cycle complete status is monitored by reading input register $0096. A value of 0 indicates the cycle
is active, while a value of 1 indicates the cycle is complete.
Reading the discrete input addresses-$0000 - $00003 monitors the hardware states of the external inputs
Event 1-4. For details on the return values see 5.2.2 [02] Read Input Discretes. Since these inputs are
active low switch inputs, a returned value of 1 (or on) means the input is active (electrically pulled low).
Reading the discrete output addresses-$0000 - $00003 monitors the hardware states of relays 1-4. For
details on the return values see 5.2.1 [01] Read Outputs.
The audible annunciator can be monitored via input register $0097. A value of 0 indicates the audible
annunciator is off, while a value of 1 indicates on. Acknowledgement of alarms and cycle complete
audible annunciation is handled through the alarm acknowledge holding register ($0007). Writing any
non-zero value to this register will acknowledge the alarm. This register emulates the pressing of the
Page/Reset key during an audible alarm condition.
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