EET3370 Sequencer Notes

Figure 13-7 Sequencer Output (SQO) Instruction

# indicates a file rather than a word.

Using a dot as a delimiter indicates a word.

0's in the mask results in ORing the outputs with O which keeps the outputs in the same state they were in before the SQO instruction. This prevents the SQO from affecting those bits and then outputs are not changed by the SQO and therefore can be controlled by other instructions. 1's in the mask result in ANDing 1 with the appropriate bit of a word in the position file and transferring the results to the output

Two important control word bits are the EN bit 15 (enable) and the DN bit 13 (sequencer is in last position and has finished transferring bits to destination file).

When the processor is first switched on or changed from the program to the run mode, SQO instruction operation depends on whether the rung is true or false on the first scan.

If the rung is true and Position = 0, the instruction transfers data for position 0 and increments to the next position.

If the rung is false on the first scan, the instruction does not transfer the data or increment the position.

After the first scan on the next false to true:

1- the position is incremented

2- the data is transferred through the mask to the destination address

3-as long as the rung is true, it continues to transfer the same data without
changing the position.

4-when the rung goes false it stop affecting the output

The SQO will always reset to position 1 after it has gone through the last position if the processor is left in the run mode.

Let’s go over this again. Normally when the SQO instruction sees a false-to-true transition, it increments the position value first and then transfers a word of information to the destination through a mask. See Figure A below. The first scan however is special and determines if position 0 is used. If the instruction is at position 0 and the SQO sees a true on the first scan, it will not increment the position, but will first transfer the word of information at position 0 to the destination through a mask. If, on the first scan, it sees a false, it will not change the position or transfer the word at position 0 to the destination. After the first scan, it will go in normal operation therefore if the SQO instruction sees a false to true transition it will increment to position 1 and transfer a word of information to the destination through a mask.

Figure A

Figure 13-8 SQO Data Flow

Figure 13-9 Destination Data Before and After Instruction Indexed

The SQI is used to detect when a process gets to a certain position and then to act. The SQI is used to compare input information words through a mask, and if the information word is the same as its file word for that position, it energizes an output. The SQI instruction doesn't affect its' own control word. The control word which determines position must be changed by other programming.

Figure 13-10 Sequencer Input (SQI) Instruction

Figure 13-11 Data Comparison for SQI Instruction

Notice the control word is the same for both instructions. If the input word I: 025 matches the word for the present position in file B3:010, then SQO will read the work of the present position in file B3:050 and transfer this information through the mask word found in B3:100 to the output word O:050. Notice after the transfer both the SQI and SQO control word will advance to the next position. The SQO causes this to happen since they both have the same control word.

Figure 13-12 Sequencer Output Driving Sequencer Input

The SQL instruction takes words of input information and loads them into a file one word at a time. Each time it sees a false to true, it will load a word and then increment the position to get ready for the next word.

Figure 13-13 Sequencer Load (SQL) Instruction

This instruction builds the file like the example below: