Electro Cam PS-4456 Absolute Gray Code Encoder - Manual (Page 4)

Gray Code — Error Free Decoding
The Gray Code chart below (Figure 2) shows the bit pat-
terns that are used to represent all 256 encoder positions.
It can be seen on this chart that from any position to any
adjacent position, only 1 bit changes state. This ensures
that the encoder inputs can be read by the control at any
point in time (even during a transition) without error.
Consider the following comparison to Binary Code:
When Gray Code advances from increment 127 to 128,
only 1 of the 8 bits changes state — bit 8. When Binary
Code advances from increment 127 to 128, all 8 bits
change states. Sampling the Binary bits during this transi-
tion could result in a very large decoding error. Sampling
the Gray Code bits during this transition would yield either
127 or 128, depending only on bit 8.
8 Bit Gray Code Table
Figure 2
INC DEG GRAY CODE BINARY
127 178.6 01000000 01111111
128 180.0 11000000 10000000
4
Refer to the table below to understand the relationship
between the
increment (integer), degrees and binary
numbers. Use this table as a guide for setup and trouble-
shooting your Gray Code system.
■ INC (increment) column represents the integer value
to which the Gray Code is equal. The increments
are 0 to 255 (256 total) that repeat or cycle. (At 255,
the next number change is 0, increment to 255, then
repeat the cycle over again).
■ DEG (degree) column represents the actual degree
position that the Gray Code is indicating.
■ Gray Code column shows the Gray Code value
for that particular position. This Gray Code binary
number is the same as the Gray Code inputs status,
1 = ON and 0 = OFF.
Because the Gray Code value is also a graphic repre-
sentation of the input status, it is an invaluable tool in
checking the position or troubleshooting.
INC DEG GRAYCODE
0 0.0 00000000
1 1.4 00000001
2 2.8 00000011
3 4.2 00000010
4 5.6 00000110
5 7.0 00000111
6 8.4 00000101
7 9.8 00000100
8 11.3 00001100
9 12.7 00001101
10 14.1 00001111
11 15.5 00001110
12 16.9 00001010
13 18.3 00001011
14 19.7 00001001
15 21.1 00001000
16 22.5 00011000
17 23.9 00011001
18 25.3 00011011
19 26.7 00011010
20 28.1 00011110
21 29.5 00011111
22 30.9 00011101
23 32.3 00011100
24 33.8 00010100
25 35.2 00010101
26 36.6 00010111
27 38.0 00010110
28 39.4 00010010
29 40.8 00010011
30 42.2 00010001
31 43.6 00010000
32 45.0 00110000
33 46.4 00110001
34 47.8 00110011
35 49.2 00110010
36 50.6 00110110
37 52.0 00110111
38 53.4 00110101
39 54.8 00110100
40 56.3 00111100
41 57.7 00111101
42 59.1 00111111
43 60.5 00111110
44 61.9 00111010
INC DEG GRAYCODE
45 63.3 00111011
46 64.7 00111001
47 66.1 00111000
48 67.5 00101000
49 68.9 00101001
50 70.3 00101011
51 71.7 00101010
52 73.1 00101110
53 74.5 00101111
54 75.9 00101101
55 77.3 00101100
56 78.8 00100100
57 80.2 00100101
58 81.6 00100111
59 83.0 00100110
60 84.4 00100010
61 85.8 00100011
62 87.2 00100001
63 88 6 00100000
64 90.0 01100000
65 91.4 01100001
66 92.8 01100011
67 94.2 01100010
68 95.6 01100110
69 97.0 01100111
70 98.4 01100101
71 99.8 01100100
72 101.3 01101100
73 102.7 01101101
74 104.1 01101111
75 105.5 01101110
76 106.9 01101010
77 108.3 01101011
78 109.7 01101001
79 111.1 01101000
80 112.5 01111000
81 113.9 01111001
82 115.3 01111011
83 116.7 01111010
84 118.1 01111110
85 119.5 01111111
86 120.9 01111101
87 122.3 01111100
88 123.8 01110100
89 125.2 01110101
INC DEG GRAYCODE
90 126.6 01110111
91 128.0 01110110
92 129.4 01110010
93 130.8 01110011
94 132.2 01110001
95 133.6 01110000
96 135.0 01010000
97 136.4 01010001
98 137.8 01010011
99 139.2 01010010
100 140.6 01010110
101 142.0 01010111
102 143.4 01010101
103 144.8 01010100
104 146.3 01011100
105 147.7 01011101
106 149.1 01011111
107 150.5 01011110
108 151.9 01011010
109 153.3 01011011
110 154.7 01011001
111 156.1 01011000
112 157.5 01001000
113 158.9 01001001
114 160.3 01001011
115 161.7 01001010
116 163.1 01001110
117 164.5 01001111
118 165.9 01001101
119 167.3 01001100
120 168.8 01000100
121 170.2 01000101
122 171.6 01000111
123 173.0 01000110
124 174.4 01000010
125 175.8 01000011
126 177.2 01000001
127 178.6 01000000
128 180.0 11000000
129 181.4 11000001
130 182.8 11000011
131 184.2 11000010
132 185.6 11000110
133 187.0 11000111
134 188.4 11000101
INC DEG GRAYCODE
135 189.8 11000100
136 191.3 11001100
137 192.7 11001101
138 194.1 11001111
139 195.5 11001110
140 196.9 11001010
141 198.3 11001011
142 199.7 11001001
143 201.1 11001000
144 202.5 11011000
145 203.9 11011001
146 205.3 11011011
147 206.7 11011010
148 208.1 11011110
149 209.5 11011111
150 210.9 11011101
151 212.3 11011100
152 213.8 11010100
153 215.2 11010101
154 216.6 11010111
155 218.0 11010110
156 219.4 11010010
157 220.8 11010011
158 222.2 11010001
159 223.6 11010000
160 225.0 11110000
161 226.4 11110001
162 227.8 11110011
163 229.2 11110010
164 230.6 11110110
165 232.0 11110111
166 233.4 11110101
167 234.8 11110100
168 236.3 11111100
169 237.7 11111101
170 239.1 11111111
171 240.5 11111110
172 241.9 11111010
173 243.3 11111011
174 244.7 11111001
175 246.1 11111000
176 247.5 11101000
177 248.9 11101001
178 250.3 11101011
179 251.7 11101010
INC DEG GRAYCODE
180 253.1 11101110
181 254.5 11101111
182 255.9 11101101
183 257.3 11101100
184 258.8 11100100
185 260.2 11100101
186 261.6 11100111
187 263.0 11100110
188 264.4 11100010
189 265.8 11100011
190 267.2 11100001
191 268.6 11100000
192 270.0 10100000
193 271.4 10100001
194 272.8 10100011
195 274.2 10100010
196 275.6 10100110
197 277.0 10100111
198 278.4 10100101
199 279.8 10100100
200 281.3 10101100
201 282.7 10101101
202 284.1 10101111
203 285.5 10101110
204 286.9 10101010
205 288.3 10101011
206 289.7 10101001
207 291.1 10101000
208 292.5 10111000
209 293.9 10111001
210 295.3 10111011
211 296.7 10111010
212 298.1 10111110
213 299.5 10111111
214 300.9 10111101
215 302.3 10111100
216 303.8 10110100
217 305.2 10110101
218 306.6 10110111
219 308.0 10110110
220 309.4 10110010
221 310.8 10110011
222 312.2 10110001
223 313.6 10110000
224 315.0 10010000
INC DEG GRAYCODE
225 316.4 10010001
226 317.8 10010011
227 319.2 10010010
228 320.6 10010110
229 322.0 10010111
230 323.4 10010101
231 324.8 10010100
232 326.3 10011100
233 327.7 10011101
234 329.1 10011111
235 330.5 10011110
236 331.9 10011010
237 333.3 10011011
238 334.7 10011001
239 336.1 10011000
240 337.5 10001000
241 338.9 10001001
242 340.3 10001011
243 341.7 10001010
244 343.1 10001110
245 344.5 10001111
246 345.9 10001101
247 347.3 10001100
248 348.8 10000100
249 350.2 10000101
250 351.6 10000111
251 353.0 10000110
252 354.4 10000010
253 355.8 10000011
254 357.2 10000001
255 358.6 10000000