Specifications

Functional Description 2-3
Latching alarms are turned off with the Clear Alarms (CA) command or if the
opposite alarm limit is exceeded.
The state of the alarms may be read with the Digital Input (DI) command.
Also, the alarm outputs may be used to activate digital outputs on the module
to turn on alarms or to perform simple control functions. The alarm outputs
are shared with the general purpose digital output bits DO0 and DO1. To
connect the alarm outputs to the module connector, the Enable Alarm (EA)
command is used. The connector pins may be switched back to the general-
purpose digital outputs using the Disable Alarms (DA) command. The EA/
DA selection is nonvolatile.
The general-purpose digital outputs are open-collector transistor switches
that may be controlled by the host with the Digital Output (DO) command.
They are designed to activate external solid-state relays to control AC or DC
power circuits. The output may also be used to interface to other logic-level
devices. The number of digital outputs available depends on the module
type.
The Digital Input (DI) command is used to sense the logic levels on the digital
input pins DI0-DI7. The digital inputs are used to read logic levels generated
by other devices. They are also useful to sense the state of electro-
mechanical limit switches. The number of digital inputs available varies with
the module type.
The DI0 input is shared with the input to the Event Counter. The Event
Counter accumulates the number of positive transitions that occur on the
DI0/EV connector pin. The counter can accumulate up to 9999999 (decimal)
events and may be read with the Read Events (RE) command. The counter
input is filtered and uses a Schmitt-trigger input to provide a bounce-free
input for mechanical switches. The counter value may be zeroed with the
Clear Events (CE) command or the write-protected Events Clear (EC)
command.