Can't see valves connected to a SMC EX250 SEN1 unit?

[drbrain]

I have a SMC EX250 SEN1 unit attached to an array of solenoid valves as seen in the picture below:

 I am using a python package called CPPPO (https://github.com/pjkundert/cpppo) to talk to it. I have been able to successfully poll some information, such as its product name (example below), with this package but some reason I cannot seem to get any form of response from the valves.

 ^Successful request for product name

Based on information that I have gleamed from around the internet, I think I should be using Instance : 100, Class :4, Attribute : 3 to get it to send me back an array of information from the valves, but instead it returns type None back.

^Unsuccessful request for Valve data (sorry I should have changed 'product_name' to 'valve_array')

Does anyone have any experience with this sort of thing? Sorry I am a complete beginner with these things. Any and all help would be greatly appreciated.