FX Series Programmable Controllers | Devices in Detail 4 |
Assigning grouped bit devices:
As already explained, bit devices can be grouped into 4 bit units. The “n” in KnM0 defines the number of groups of 4 bits to be combined for data operation. K1 to K4 are allowed for 16bit data operations but K1 to K8 are valid for 32bit operations.
K2M0, for example identifies 2 groups of 4 bits; M0 to M3 and M4 to M7, giving a total of 8 bit devices or 1 byte. The diagram below identifies more examples of Kn✰ use.
X37 X36 X35 X34 X33 X32X31X30 | X16 X15 X14 X13 X12 X11 X10 X7 | X6 | X5 | X4 | X3 | X2 | X1 | X0 | ||||||||||||
0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 0 |
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| K1X6 |
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| K1X0 |
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| K3X0 |
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| K8X0 |
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K1X0 | : | X0 to X3 ➯ 4 bit devices with a head address of X0 |
K1X6 | : | X6 to X11 ➯ 4 bit devices with a head address of X6 |
K3X0 | : | X0 to X13 ➯ 12 bit devices with a head address of X0 |
K8X0 | : | X0 to X37 ➯ 32 bit devices with a head address of X0 |
Moving grouped bit devices:
•If a data move involves taking source data and moving it into a destination which is smaller than the original source, then the overflowing source data is ignored. For example;
If K3M20 is moved to K1M0 then only M20 to M23 or K1M20 is actually moved. The remaining data K2M24 or M24 to M31 is ignored.
Assigning I/O:
•Any value taken from the available range of devices can be used for the head address ‘marker’ of a bit device group. However, it is recommended to use a 0 (zero) in the lowest digit place of X and Y devices (X0, X10, X20.....etc). For M and S devices, use of a multiple of “8” is the most device efficient. However, because the use of such numbers may lead to confusion in assigning device numbers, it recommended to use a multiple of “10”. This will allow good correlation to X and Y devices.
