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Crosstalk between SIO4/SIO4A ?


Bob Fleming Apr 6, 2018 09:58 PM

I have CR1000 dataloggers that have been running stably for some time using 2 SDM-SIO4s (old style).  I am trying to add an SIO4A (new style) to the SDM bus.  The old SIO4s are using SDM addresses 1 and 2 and the new SIO4A is using SDM address 3.  I also have an SDM-CD16AC on address 11.  I just upgraded to OS v. 32.02.

After connecting the SIO4A, when running a CRBASIC program that accesses the SDM-SIO4s (old-style), I get a lot of bursty noise on at least 1 SIO4A ports when trying to "talk through" via connected instruments via Loggernet.   We are calling the PulseRead instruction on the SIO4 IRQ ports twice a second, though serial traffic on the SIO4s is pretty low, maybe 1-2 kbytes  per hour total.  

When running a program that does not access the old-style SDM-SIO4's, I get no such noise on the SIO4A when talking through.  Traffic to the SDM-CD16AC doesn't seem to have any effect.

Am I seeing crosstalk or interference between the old and new SIO4s?  The bus wiring is very short, a couple of inches between components on the SDM bus.

I also notice that (when the new SIO4A is installed, regardless of program running) if I try to address command mode via talk-through on the (old) SIO4 through the loggernet terminal emulator, I cannot --

...12: COM4
14: SDM-SIO4
32..47: SDM-SIO1
Select: 14
Enter SDM Address (0..15): 2
Enter Port (0..4): 0
Enter Param (0..8191): 0
opening sio4 0,0,0
Exiting

CR1000>

I am immediately returned to the prompt.  The phrase "opening sio4 0,0,0" makes me think there is a bus conflict or addressing issue of some kind.

I wondered if anyone has seen similar issues, or has experienced old SIO4s working successfully with new SIO4A's.


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