Agilent Technologies E4374A Special Functions, Wiring Guidelines, 2. Digital I/O Connections

2 - Installation

Isolated Output When outputs are configured for optically isolated mode, they are open-collector outputs capable of sinking 1.6mA at 0.4V, and can be used up to 24V. Adjacent pin pairs starting with pin 0 are the plus and minus output of an optical isolator. This allows for up to 8 isolated outputs, on adjacent pin pairs 0-1, 2-3, 4-5 etc. Because these are dedicated pairs, pins 1 and 2 cannot be combined as an isolated output.

Special Functions

External Fault Input

When true, this signal stops the cell forming sequence due to an external fault condition. It also sets the external fault output signal true. This signal can be connected to a sensor such as a fire detector. It can also be connected to the external fault output of another Agilent MCCD so that it can respond to a fault in another mainframe.

External Fault Output

This signal is asserted true when an external fault occurs. It can be connected to external equipment such as a fire alarm. It can also be connected to the external fault input of another mainframe so that a fault in one mainframe can shut down other mainframes. A cfProtectClear command clears this signal.

External Interlock	When true, this signal stops the cell forming sequence, but because the stop was not
	due to a fault condition, it does not set the external fault output signal true. This
	level-sensitive signal can be connected to an external stop or pause switch to allow
	an operator or mechanical device to stop a cell forming sequence. When the signal
	is removed, the sequence continues.
External Trigger	This external trigger input is used to start the cell forming sequence.
Power Fail	Depending on how the system is configured, when true, this input signal will cause
	the Agilent MCCD to perform a shutdown, at which time it saves its state for a later
	restart. A power fail output signal is also available to indicate when the shutdown
	state has been saved.

Wiring Guidelines

Connection for the 16 digital I/O signals are through two 10-pin Phoenix/Weidmuller style connectors. The connectors have screw terminals for making wire connections and are detachable. Digital I/O lines 0 through 7 are on connector 1; digital I/O lines 8 through 15 are on connector 2. There are two common terminals on each connector for ground or the return connection.

⊥ 15 14 13 12 11 10 9 8 ⊥ ⊥ 7 6 5 4 3 2 1 0 ⊥

Figure 2-2. Digital I/O Connections

The following figure illustrates the internal circuits of the digital I/O connector. When used as a digital in put (A), the external circuit connected to the digital input pin can be TTL, AS, CMOS, HC, or a simple switch that connects the digital input to the common terminal.

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