I searched all over the Honeywell website and was unable to locate any information on a Honeywell EM150. Perhaps there is another number on the part? I'm including their Customer Support number in this message. They should be able to help you identify the part number and help you locate a wiring diagram through their technical support department.
For further questions, contact Honeywell Customer Care at 1-877-271-8620
https://yourhome.honeywell.com/home/Applications/ContactUs.aspx