Display System (Touch Screen Display); Connector Terminals - A.O. Smith 100 Series Service Handbook

DISPLAY SYSTEM (TOUCH SCREEN DISPLAY)

The Display System is a microprocessor-based color touchscreen Operator Interface (OI) display that provide an operator interface
for monitoring and configuring parameters such as burner control sequence, flame signal, diagnostics, historical files, and faults in
the Control System. It can be used to monitor an individual boiler/water heater but is primarily used for multiple boiler/water heater
applications in a lead/lag arrangement. Wiring connections to the Display System are through a removable 8-pin wiring header.
Electrical Ratings:
1. Input Voltage: 18 – 30 Vac (24Vac nominal), 50/60 Hz.
2. Input Current: 500 mA max.
3. Power consumption: 12W max.
4. Operating Temperature: -4 to 158 ºF (-20 to 70 ºC)
5. Storage/Shipping Temperature: -22 to 176 ºF (-30 to 80 ºC)
6. Humidity: 90% RH, non-condensing.
7. Enclosure rating: IP10 / NEMA 1
8. Approvals:
• FCC Part 15, Class A Digital Device.
• Underwriter's Laboratories, Inc. (UL) (cUL) Component Recognized (for non-continuous operation): File Number MH17367
(MJAT2, MJAT8).

CONNECTOR TERMINALS

The Display System must be appropriately wired for both power and communications.
The communication is done over two RS-485 bus:
• COM1 is connected directly to the Control Board J3 connector to either Modbus (MB1 or MB2).
• COM2: A bus to the Building Automation System.
Refer to the Table 4 for 8-pin Connector Terminals.
* These 3 terminals are connected internally and can be connected to earth ground.
FIGURE 18. DISPLAY CONNECTOR TERMINALS
TABLE 4. 8-PIN CONNECTOR TERMINALS
PIN #
1
2
3
4
5
6
7
8
Servicing should only be performed by a Qualified Service Agent
FUNCTION
COM1 A
COM1 B
COM1 C*
COM2 A
COM2 B
COM2 C*
24 VAC Common*
24 VAC Power
29