Tektronix ECO 422, Instruction Manual

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Operating Basics
2–6
ECO 422
Fault Reporting – and + It is normally open, indicating that everything is good. It
will close in the cases of: loss of power to the ECO 422 or one (or more) input
signals are bad. The fault is latched and will remain until the fault is cleared.
This fault reporting system follows SMPTE 269M guidelines except the
interface is 2 pins of the Remote connector (7 & 8) instead of the standard
isolated BNC connector and there is no pulsing. When in the open state, the
leakage across the closure is less than 100
µ
A at any voltage from 0 to 5 VDC.
The closure is able to withstand 24 VDC in the open state without damage. In
the closed state, the maximum voltage drop across the closure should not exceed
2 V at 20 mA. The sensing device should not supply more than 20 mA of current
to the reporting device. To provide compliance with the standard, wire a BNC
connector adapter as shown in Figure 2–5.
Figure 2–5: Wiring Required to Conform with SMPTE Fault Reporting
Reference
Operating Basics
In normal operation, the ECO 422 is basically a switch that triggers whenever an
error occurs in any channel. All 11 Channels switch at the same time.
If any channel is not being used, it is mandatory that its checking function be
disabled. Otherwise it will always trigger an error and the ECO 422 will not
operate properly.
This section covers the state machine discussions (what will happen when some
signals go bad) and how to adjust the user-defined inputs.