Reading IDC16 with OptoMMP

I am trying to read an IDC16 module’s input via the OptoMMP DLL. I am finding that the results are erratic. I have a voltage applied to one of the inputs and sometimes I see the input as being “active” and other times I don’t. I don’t know what I did but it started working. I also noticed in PAC Manager using the inspector, the Refresh button would sometimes clear the display area without rewriting the input values.

Hi Bytemaster,

Welcome to the forums!

Usually (almost always) this kind of “flaky” behavior indicates too-low voltage on the rack. It’s so common, we even made a video about it:


Link to same video on YouTube, click here

Are you using an Opto 22 power supply for that rack? I’m assuming here you mean you have a SNAP-IDC16 on a rack w/a brain, perhaps a SNAP-PAC-EB2?

Our power supplies are more expensive than others, but they’re also more likely to give you a nice consistent voltage that the brain & modules need.

If that’s not it, you’ll want to contact our Product Support team (it’s free!). They’ll have you use PAC Manager to have a look at the “Status Read” area which shows your hardware/firmware versions. Also, toward the bottom (if you scroll down in the Status Read area) you’ll see info like this that can be helpful for troubleshooting:

0xFFFF F030 007C   Smart Modules Present                  0x0098
                   (analog, serial, etc.) 
0xFFFF F030 011C   PID Loops Supported                    96
0xFFFF F030 0148   Digital Modules Supported              16

0xFFFF F030 0100   Arcnet Reconfigs Detected              0
0xFFFF F030 0104   Arcnet Reconfigs Initiated by I/O Unit 0
0xFFFF F030 0120   Arcnet Transmit Attempts Since Powerup 2172696
0xFFFF F030 0128   Arcnet ACKs                            2172683
0xFFFF F030 0134   Arcnet Timeouts                        0
0xFFFF F030 0124   Arcnet Other (node not found, etc)     13
0xFFFF F030 0130   Arcnet Timeout Value (msec.)           0
0xFFFF F030 0138   Arcnet Receive Interrupts              2172683

0xFFFF F030 0110   Ethernet MAC Resets Since Powerup      0
0xFFFF F030 0114   Dig. Output Point Resets Since Powerup 0
0xFFFF F030 0118   Dig. Interrupt Failures Since Powerup  0

0xFFFF F030 0140   Analog & High Density Digital Scanner  0.990 msec/scan
0xFFFF F030 0144   4-Channel Digital Scanner              1.000 msec/scan

0xFFFF F030 00C0   Module  0 - Times Discovered           0
0xFFFF F030 00C4   Module  1 - Times Discovered           0
0xFFFF F030 00C8   Module  2 - Times Discovered           0
0xFFFF F030 00CC   Module  3 - Times Discovered           0
0xFFFF F030 00D0   Module  4 - Times Discovered           0
0xFFFF F030 00D4   Module  5 - Times Discovered           0
0xFFFF F030 00D8   Module  6 - Times Discovered           0
0xFFFF F030 00DC   Module  7 - Times Discovered           0
0xFFFF F030 00E0   Module  8 - Times Discovered           0
0xFFFF F030 00E4   Module  9 - Times Discovered           0
0xFFFF F030 00E8   Module 10 - Times Discovered           0
0xFFFF F030 00EC   Module 11 - Times Discovered           0
0xFFFF F030 00F0   Module 12 - Times Discovered           0
0xFFFF F030 00F4   Module 13 - Times Discovered           0
0xFFFF F030 00F8   Module 14 - Times Discovered           0
0xFFFF F030 00FC   Module 15 - Times Discovered           0


I am trying to use a SNAP-PAC-R1 on a SNAP-PAC-RACK16 with low density DI modules (more than 8) as a master and a SNAP-PAC-R1 on a SNAP-M64 backplane as slave. Every second there are “arcnet reconfigs detected” and “Arcnet Reconfigs Initiated by I/O Unit”. Power is 5.01 V.
Although according to te optoMMP protocol guide it says:
“ARCNET reconfigs initiated by I/O unit. Error on the rack’s ARCNET
bus. (Does not apply to E1s or E2s.) Not a concern unless it happens
frequently. If there are no analog, serial, high-density digital, or PID
modules on the rack, ignore it. If there is at least one of these modules
on the rack, make sure the rack has adequate voltage.”, I am concerned that it is not going to work.
Right now it is running in test configuration. Can you assure me that this will run in the real world?
regards, Berry

Have you contacted our support group with this? (support@opto22 dot com)
They have some deep knowledge of the error you are seeing and may be able to help you resolve it.

Sorry for the late reply. I’m back at the same issue after spending time on other issues. Yes, I just did. Hopefully something comes out.