Model 7002Switch System Instruction Manual - Advanced Test ...

Theory of OperationID data is contained within an EEPROM which is located onthe relay card. The system performs the following sequenceof operations at power-up in order to read the information:1. The IDDATA line (pin 6 of the EEPROM located on therelay card) is set low while the IDCLK line (pin 5) isheld high. This action initiates a start command for theROM located on the relay card to transmit data seriallyto the mainframe (see Figure 6-5).2. The mainframe sends the ROM address location to beread over the IDDATA line. The ROM then transmits anacknowledge signal back to the mainframe, and thentransmits data at that location back to the mainframe (referback to Figure 6-4).3. The mainframe then transmits an acknowledge signalindicating that it requires more data. The ROM on therelay card will then sequentially transmit data after eachacknowledge signal it receives.4. Once all data are received, the mainframe sends a stopcommand. The stop command consists of a low-to-hightransition of the IDDATA line while the IDCLK line isheld high (see Figure 6-6).From Digital Board+14.6V +6V +5VFromDigitalBoardRelay CLK, DataStrobe, Enable4Model 701X Switch CardInterface4 Analog Banks3 HI, LO, GuardTo next slotof 701XinterfaceTo/FromDigitalBoardID CLK 2ID DataR/W, CS, I/O Data3+6VModel 705/6 Switch CardInterface3 Relay CLK, Data, Strobe48 Drive lines4 Drive linesRelay Drivers5841 4Relay Driver5841Figure 6-4Block diagram ⎯ backplane interface (one slot)6-7