Rob MacLeod, Bonnie Punske, Bruce Steadman
This is an attempt to describe the layout of channels in the CVRTI multiplexers (MUX) as they come out on the oscilloscope displays and in the data stream of the acquisition files. The description is targeted at the large MUXs we now use routinely so is not likely to be correct for a small (e.g., 256 channel) MUX system if you are stuck using one.
We begin with a short intro in Section 2 and then describe in Section 3 some simple tools for making your own MUX mapping files. For those who really want to know, you can find all the ugly details in Section 4.
Another way to picture the mapping between leads of each bank and the channels in the multiplexed datastream is by the following equations:
| Bank | Mapping | Example |
| Master #1 | ch = (l - 1)*4 + 1 | 1, 5, 9, 13,...,1017, 1021 |
| Master #2 | ch = (l - 1)*4 + 3 | 3, 7, 11, 15,...,1023 |
| Slave #1 | ch = (l - 1)*4 + 2 | 2, 6, 10, 14,...,1022 |
| Slave #1 | ch = (l - 1)*4 + 4 | 4, 8, 12, 16,...,1024 |
We have some software for creating MUX mapping files that should take care of most needs. The program (script actually) that does this is called makemuxmapping and it has the following format:
Usage: makemuxmapping.sh -t numtank -s numsock -n numneedles -m 512/1024 -f
-t to set number of tank electrodes
-s to set number of sock electrodes
-n to set number of needles
-m to set MUX config (512 or 1024 leads)
-f for a full mapping file (with padding)
The filename conventions that makemuxmapping assumes are:
See the next section for examples of filenames.
To make an andy3 mapping with 374 leads and a 490 lead sock in a 1024 MUX.
> makemuxmapping.sh -t 374 -s 490 -m 1024 Wrote 192 channels of tank Wrote 182 channels of secondary tank Wrote 490 channels of sock For a total of 864 channels Finished with andy3_374t_490s_1024.mux
To have the same contents, but padded for use in the experiment:
> makemuxmapping.sh -t 374 -s 490 -m 1024 -f Wrote 192 channels of tank Wrote 182 channels of secondary tank Wrote 490 channels of sock Wrote 160 channels of end fill For a total of 1024 channels Finished with andy3_374t_490s_1024_full.mux
To make a mapping file for a 490 lead sock in the 512 channel configuration:
> makemuxmapping.sh -s 490 -m 512 -f Wrote 490 channels of sock Wrote 22 channels of end fill For a total of 512 channels Finished with sock_490s_full.mux
And to now add 22 needles to this configuration
> makemuxmapping.sh -s 490 -n 22 -m 512 -f Wrote 490 channels of sock Wrote 22 channels of end fill For a total of 512 channels Finished with sock_490s_22n_full.mux
In order to see the data we record in the proper order, or even to monitor leads during an experiment, we need to have some methods for untangling all these leads. For that we have ``mux mapping'' files, and there are a lot of them, one for each type of electrode configuration.
Mux mapping files contain a list of channel numbers. The order of the channels is the same as the order of the channels we want to have (e.g., in an output file). The value of the channels in the list indicate the source of that channel in the MUX itself.
Perhaps the best way to see this in action is in an example. Here is a mux mapping file for a 128-lead sock and 22 10-pole needles. We break the mux mapping file into sections to make this ordering clear.
First the 128 sock leads:
512 channels 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 109 111 113 115 117 119 121 123 125 127 129 131 133 135 137 139 141 143 145 147 149 151 153 155 157 159 161 163 165 167 169 171 173 175 177 179 181 183 185 187 189 191 193 195 197 199 201 203 205 207 209 211 213 215 217 219 221 223 225 227 229 231 233 235 237 239 241 243 245 247 249 251 253 255
Followed by the 22, 10-pole needles, which require 220 channels. These are plugged into the second bank:
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140 142 144 146 148 150 152 154 156 158 160 162 164 166 168 170 172 174 176 178 180 182 184 186 188 190 192 194 196 198 200 202 204 206 208 210 212 214 216 218 220 222 224 226 228 230 232 234 236 238 240 242 244 246 248 250 252 254 256 258 260 262 264 266 268 270 272 274 276 278 280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318 320 322 324 326 328 330 332 334 336 338 340 342 344 346 348 350 352 354 356 358 360 362 364 366 368 370 372 374 376 378 380 382 384 386 388 390 392 394 396 398 400 402 404 406 408 410 412 414 416 418 420 422 424 426 428 430 432 434 436 438 440
Now, we fill out the rest of the mapping file with all the other leads, starting with the remaining ones from bank #1.
257 259 261 263
265 267 269 271 273 275 277 279
281 283 285 287 289 291 293 295
297 299 301 303 305 307 309 311
313 315 317 319 321 323 325 327
329 331 333 335 337 339 341 343
345 347 349 351 353 355 357 359
361 363 365 367 369 371 373 375
377 379 381 383 385 387 389 391
393 395 397 399 401 403 405 407
409 411 413 415 417 419 421 423
425 427 429 431 433 435 437 439
441 443 445 447 449 451 453 455
457 459 461 463 465 467 469 471
473 475 477 479 481 483 485 487
489 491 493 495 497 499 501 503
505 507 509 511
and then all those left from bank #1.
442 444 446 448
450 452 454 456 458 460 462 464
466 468 470 472 474 476 478 480
482 484 486 488 490 492 494 496
498 500 502 504 506 508 510 512
The reason for padding the file this way is that the data acquisition program requires the number of entries to match the number of channels--this way there are no unidentified channels. For remapping the data to create time series files, it makes more sense to shed all the empty channels and so the resulting mux mapping file contains only those necessary (in this case 128 + 220 = 348. The file looks like this:
348 channels 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 109 111 113 115 117 119 121 123 125 127 129 131 133 135 137 139 141 143 145 147 149 151 153 155 157 159 161 163 165 167 169 171 173 175 177 179 181 183 185 187 189 191 193 195 197 199 201 203 205 207 209 211 213 215 217 219 221 223 225 227 229 231 233 235 237 239 241 243 245 247 249 251 253 255 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140 142 144 146 148 150 152 154 156 158 160 162 164 166 168 170 172 174 176 178 180 182 184 186 188 190 192 194 196 198 200 202 204 206 208 210 212 214 216 218 220 222 224 226 228 230 232 234 236 238 240 242 244 246 248 250 252 254 256 258 260 262 264 266 268 270 272 274 276 278 280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318 320 322 324 326 328 330 332 334 336 338 340 342 344 346 348 350 352 354 356 358 360 362 364 366 368 370 372 374 376 378 380 382 384 386 388 390 392 394 396 398 400 402 404 406 408 410 412 414 416 418 420 422 424 426 428 430 432 434 436 438 440
For the 1024 channel configuration, the file for the same leads looks completely different! If we left all the connectors in the same place and just attached the second MUX, the resulting mux mapping file would be (the version without padding) as follows:
384 channels 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97 101 105 109 113 117 121 125 129 133 137 141 145 149 153 157 161 165 169 173 177 181 185 189 193 197 201 205 209 213 217 221 225 229 233 237 241 245 249 253 257 261 265 269 273 277 281 285 289 293 297 301 305 309 313 317 321 325 329 333 337 341 345 349 353 357 361 365 369 373 377 381 385 389 393 397 401 405 409 413 417 421 425 429 433 437 441 445 449 453 457 461 465 469 473 477 481 485 489 493 497 501 505 509 2 6 10 14 18 22 26 30 34 38 42 46 50 54 58 62 66 70 74 78 82 86 90 94 98 102 106 110 114 118 122 126 130 134 138 142 146 150 154 158 162 166 170 174 178 182 186 190 194 198 202 206 210 214 218 222 226 230 234 238 242 246 250 254 258 262 266 270 274 278 282 286 290 294 298 302 306 310 314 318 322 326 330 334 338 342 346 350 354 358 362 366 370 374 378 382 386 390 394 398 402 406 410 414 418 422 426 430 434 438 442 446 450 454 458 462 466 470 474 478 482 486 490 494 498 502 506 510 514 518 522 526 530 534 538 542 546 550 554 558 562 566 570 574 578 582 586 590 594 598 602 606 610 614 618 622 626 630 634 638 642 646 650 654 658 662 666 670 674 678 682 686 690 694 698 702 706 710 714 718 722 726 730 734 738 742 746 750 754 758 762 766 770 774 778 782 786 790 794 798 802 806 810 814 818 822 826 830 834 838 842 846 850 854 858 862 866 870 874 878
This document was generated using the LaTeX2HTML translator Version 99.2beta6 (1.42)
Copyright © 1993, 1994, 1995, 1996,
Nikos Drakos,
Computer Based Learning Unit, University of Leeds.
Copyright © 1997, 1998, 1999,
Ross Moore,
Mathematics Department, Macquarie University, Sydney.
The command line arguments were:
latex2html -split 3 -no_white -link 3 -no_navigation -nomath -html_version 3.2,math muxmapping
The translation was initiated by Rob MacLeod on 2001-01-11