The 5601ACO2 Automatic Changeovers are intended for use with two 5601MSC Master Clock/Sync Generators. The 5601ACO2 system uses latching relays to ensure maximum reliability and minimal disruption in the event of any failure. The complete system provides the highest level of security for television station video and time synchronization systems. The 5601ACO2 is a 2RU ACO for all outputs of the 5601MSC. Two power supplies are included as a standard feature, to alleviate any single point of failure concerns.
There are three switches behind the front panel for added security. There is an AUTO/MANUAL switch, a GPI/FRONT PANEL switch and an A/B select switch for manual changeover. In automatic mode, all signals from both 5601MSC are monitored to detect any abnormal signals. For example, if a level, pulse width, phase, time code error or other abnormality is detected, the 5601ACO2's circuitry will trigger and the entire bank of signals will be switched to the backup 5601MSC. In manual mode the changeover can be operated from a GPI or from the front panel switch. LEDs provide status information as to the health of the two 5601MSC, together with indication as to which one is active. In addition, two GPO outputs indicate which master is active and when the inputs from both masters are not the same.
The 5601ACO2 features selectable voting via VistaLINK® for autochangeover features. Individual inputs may selectively be included or excluded in the voting process to drive autochangeover logic (feature only available on 5601ACO2 and 5600ACO2 models).
Each 5601MSC is equipped with 2 GPI inputs and 2 GPO outputs. To facilitate installation, these connections are brought through to a 2x6 pin terminal block on the 5601ACO2. The outputs from the 5601MSC are passed straight through the 5601ACO2s. The inputs to the 5601MSC's are internally split by a 'Y' connector, to ensure that both 5601MSC's receive the same GPI contact closures.
In the event of a changeover occurrence, it is necessary that all outputs on one 5601MSC have the same timing as those on the other. Identical timing for both 5601MSC's is assured by locking both to the same frequency and phase source (e.g. GPS or by genlocking one 5601MSC to the other). Identical phasing of the independent black outputs is assured by implementing the "Syncro" mode in the 5601MSC's. To use this mode, both 5601MSC's syncro ports are connected together using the DB15 link cables supplied with the 5601ACO2. With both 5601MSC's operating in Syncro mode, timing adjustments made to one 5601MSC will be automatically applied to both. The link cable is connected permanently, so that any system re-timing will be applied to both 5601MSC units. (See system connection diagram at 5601MSC).