Using The E7W To Read The Status Of The Hvac Controller's 5 Output Relays - Honeywell INNCOM e7w Troubleshooting Manual

Using the e7w to read the status of the HVAC Controller's 5 Output relays

The typical Inncom HVAC controller , such as an X47, has 5 built-in relays that are used to control the HVAC
unit's heating/cooling and fan speed inputs.
The current state of these 5 relays are maintained in Byte # 12 of the 32 byte "Process Image" that is
maintained by the Room Gateway and contains the complete status of the room. The e7w's "PI5" (Process
Image) parameter can be used to read and display the current value of any of the 32 PI bytes, including the
current requested 5 output relay states in Byte 12.
Refer to Appendix 3 for details of accessing and using the e7w PI5 Parameter menu. Here, we will only focus
on using it to read Process Image offset 12. Each PI offset is a 8 bit value 0-255. For PI Offset 12, bits 4 to 0
hold the 5 relay output states. The typical functions of each relay is listed below. It is beyond the scope of this
document to go over every possible use of the relays. This information just provides the current state of the 5
output relays and it is up to you to know what each relay does for the particular HVAC unit
Bit 4 – Relay 5 (Heat Call , Reversing Valve can vary depending HVAC unit)
Bit 3 – Relay 4 (Cool Call , Compressor can vary depending HVAC unit)
Bit 2 – Relay 3 (High Fan Speed)
Bit 1 – Relay 2 (Medium Fan Speed / W2 can vary depending HVAC unit)
Bit 0 – Relay 5 (Low Fan Speed)
The typical steps of using the e7w to read the output relay states of the HVAC partner is to use the e7w to set
a desired Target temperature , allow the HVAC controller to activate the appropriate relays, then enter the
e7w PI5 parameter menu and view PI Offset 12 to see what relay outputs the HVAC controller requested to be
activated.
As an example, an X47 is configured to control a 4 Pipe FCU with 3 Fan Speeds and you do not see the actual
relays in the HVAC unit activate as you change target temperature in the room. You want to verify the X47 is
at least reacting and calling for changes to Heat/Cool and Fan speeds
1. On the e7w, raise the Target temperature to the highest allowed value (typically 80F). You would
expect Relay 5 Heat Call, and one of the 3 fan speed relays to turn on (depending on how far away the
selected target temperature is away from the actually room temperature) .
2. Access the e7w PI5 menu, and view the value of PI Offset 12.
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Value
13 April 2020
Version 9.0