Ricky Ooi

I saw there are many DAQ options for Incremental Encoder. However, is there any type of DAQ available for absolute encoder?

Hi @Fausto, You are right, the wire length between USB-1808X (Master & Slave) and the wire length between USB-1808X Master and USB-QUAD08 Slave are different. Between both USB1808X are shorter. Due to the DAQ placement method in a console, we need to get longer wire to sync between USB-1808X and USB-QUAD08.

Greetings, I have multiple DAQs (2 sets of QUAD08 & 2 sets of USB1808). To make them sync to each other, I had connect the clock signal between the master device (B0 Master) and the rest of the devices. Image below shows the connectivity of the sync connection. One of the QUAD08 (B0 Slave) is connecting to one of the motor encoder, whereas one of the USB1808 (B0 Master) is connecting to one of the analog sensor. When I run my program to begin the data collection, all the signal are perfect are sync to each other (shown in image below). However, after run for a long period (about 2 days later), I found that the signal is drift (shown in the 2nd image below). Signal Synced: Signal Drift: To have clearer picture of this, I purposely log the "Current Index" value when I execute GetStatus function to process the buffer data. Below are the observation (the index below had been converted into row index where it ranged between 0 to 200): No. Master(USB1808) Slave(USB1808) Slave(QUAD08) Slave(QUAD08) 1 100 100 99 99 2 160 160 161 160 3 200 200 199 1 . . After 2 days later . nth 130 130 150 151 nth+1 179 179 198 199 nth+2 11 11 35 35 As you can see the row index for QUAD08 had been deviated very far away from USB1808. This resulting the signal cannot be sync properly. What I observed is that the deviation is getting bigger and bigger as the DAQ is running longer. However, when i re-run my program, the signal is syncing back, but it is also drift after running for a long period. Can help to advice how should I solve this? Below are the the settings that I had deployed: C# .NET Sampling Rate: 400 Hz Scan Option for Master = ScanOptions.Continuous | ScanOptions.Background Scan Option for Slave = ScanOptions.Continuous | ScanOptions.Background | ScanOptions.ExtClock

@Fausto, I used USB1808 to measure the ICLKO signal voltage. Below is the connection I made. Then, I used DAQami to view the signal result, unfortunately, the signal voltage does not behave as you said (as shown in the image below).

@Fausto, Do I need to call "BoardConfig.SetInputPacerOut()" to enable ICLKO for USB1808?

Hi @Fausto, I did measure the clock signal voltage value before. However, I never got so high voltage before as shown by the image from you. What I got was around 0.07V, but it still managed to trigger the slave for data collection. Perhaps you can check again from your side and see if my observation is correct or not.

Hi, I have 2 USB1808 and 2 QUAD08 as shown in the diagram attached. In order to make all DAQs sync to each other, I had connected the wire between ICLKO (master) and ICLKI (slave) / XPCR (slave). When I run my program, I observed all DAQs were triggered started because I displayed out the "curIndex" obtained from "GetStatus" function in C# and there is a reading. On second time I get the "curIndex", I noticed the the reading from one of the slave device (QUAD08 B1) does not change anymore. So, I am suspecting the slave device had been lost of sync connection. After few minute of run, the "curIndex" of another slave device (QUAD08 B0) does not change anymore. At first, I was thinking this is due to my program issue. So, I purposely update my code to non-sync mode (that mean all slave DAQ are not running at ExtClock trigger), and surprisingly the DAQ worked very well. Therefore, I am confidence that this might be due to lost of sync signal by the slave device which causing by insufficient voltage/current from clock signal output by Master device. Therefore, below are my questions: 1. How many Slave DAQ can be supported by a Master USB1808 2. Any specific condition for the sync cable to connect more than 2 slave devices. 3. Any alternate solutions for this if i would like to have 4 DAQ devices to sync each other if Master device cannot support too many slave devices.

Hi @JRys, Thank for this solution. After I connect the ground, the data is now looked okay. However, after I run for about one week, the data from USB-QUAD08 is lagging than data from USB-1808. I am suspecting that USB-QUAD08 are returning the data that having large value (e.g. ~300000), so the data transfer cannot catch up with USB-1808. Not sure if you have any idea on this or not.

@JRys, Do you have any idea about this?

Hi, I tested with the sample code shared by you, I still observed drift signal between 2 DAQs. At first, this raise my thought of the CLK is not sync between 2 DAQs, therefore, I purposely place a wire to connect ICLKO pin to the analog pin of USB1808 and observe the signal. Surprisingly, the signal does not generate pulse but a small signal of approx 0.017V (you can see the sample signal in the image attached). With this observation, I also suspect maybe the software side miss out the "EXTCLOCK" setting on USB-QUAD08, so I tested this by removing the connection of XPCR from USB-QUAD08. As result, QUAD08 does return any count value from every channel. Therefore, I can justify that software side does not miss out the sync function between DAQs. In order to deep dive the sync issue, I calculated the "RowIndex" for each DAQ by using the current_index (obtained from GetStatus() function) divided by number of channels. At first, when my motor is not running, the RowIndex looks stable and almost sync to each other. When it start runing (moving forward and backward in very fast motion), the RowIndex begin unsync. I also attached two images (FirstHalf.png and SecondHalf.png) to illustrated the row index for both DAQs. It seem like QUAD08 is leading of USB1808. For your info, below is the configuration I used: PACKET_SIZE = 1024 Sampling_Rate = 400

Hi, Is CLK signal a pulse signal? or it just triggered HIGH when Master device is began.

Hi @JRys, I notice you are using different CounterDebounceTime at different case, will this the root cause for the case above? Besides, you are using Master device as the reference index number ("Index1808") for buffer comparison. Will Slave index always leading the Master device?

Hi, I had tested your solution advised, but I still having data unsync between multiple devices. Do you mind to have OEM to provide sample code that read data from different multiple devices (USB-1808 & USB-QUAD08) with sync mode for C#? For addition info, below are the mode that I used for each device: USB-1808: DaqInScan USB-QUAD08: CInScan

Alright, thank. Let me try it

Hi @JRys, Do you have any sample program that utilize multiple DAQ with different models?