Chapter 6 Applied Instructions Symbol: D ： Device in which the decoded values are S ： Source device Bit/Word stored Bit/Word n ： Number of bits whose values are decoded Word Explanation: 1. The values of the lower n bits in the source device specified by S are decoded as the values of the lower 2 n bits in D . 2. When D is a bit device, n is within the range between 1 and 8. When n is 8, the values of the 8 bits is decoded as the values of the 256 bits. (Please note that the devices in which the decoded values are stored can not be used repeatedly.) 3. When D is a word device, n is within the range between 1 and 4.
When n is 4, the values of the 4 bits is decoded as the values of the 16 bits. 4. Generally, the pulse instruction DECOP is used. Example 1: 1. When Y0.0 is switched from OFF to ON, the instruction DECO decodes the values of the 3 bits in X0.0~X0.2 as the values of the 8 bits in M100~M107. 2. After the values of the 3 bits in X0.0~X0.2 are added up, the value 3 is gotten. The third bit in M10~M1007, that is, the bit in M103, is set to 1. 3. After the instruction DECO is executed and Y0.0 is switched OFF, the values of the 8 bits in M100~M107 are unchanged.
X0.2 X0.1 4 1 2 3 3 7 6 5 4 2 1 0 M107 M106 M105 M104 M103 M102 M101 M100 6-265 API Instruction code Operand Function 1202 DECO P S, D, n Decoder Device X Y M S T C HC D L SM SR E PR K 16# “$” DF S D n Pulse instructio n 16-bit instruction (7 steps) 32-bit instruction AH500 AH500 - 0 1 1 0 0 0 0 1 0 0 0