You may wish to try this. I struggled with a 2400 for some time. After a single reading, the buffer in the 2400 contains current, voltage, ohms, a timestamp and another variable. You have to read the entire buffer of the 2400 or it ignors future commands. I struggled with the 2400 drivers also. The help files of the drivers did not describe one of the variable inputs. Finally, I figured out that it was leaving data in the buffer. I increased the variable to read all five values and it finally worked!
You will have a different solution because you are not using the drivers. But I suspect you may have the same problem. You will have to write commands to be certain you extract all measurment information for the reading. Perhaps the DMM may also have a simi
lar feature. If you do not read all the data, the systems will hang.