Hi everyone,

I am doing traffic modeling with VISSIM 10 and the COM interface. I am writing some Python scripts to run VISSIM simulations, implement some scenarios and controls, and collect data. In one step of my code, I need to collect the traffic flow measured by data collection groups and here is what I did:

vs = com.Dispatch("VISSIM.Vissim.1000")

dc = vs.Net.DataCollectionMeasurements.ItemByKey(DataCollectionGroup_ID)

flow = dc.AttValue('Vehs(Current,Max,All)')

The result is always "None" and I got really confused. I pretty much followed the sample code provided by PTV. One possible reason I can think of is that I am running single step simulation but the sample code runs continuous simulation. I run single step because I need to apply something at certain time during the simulation and I prefer not to change it.

Appreciate for any help or suggestions and thank you in advance.