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Peerless® PureFire®

PFC-850/1000/1500 MODBUS Application Supplement

NOTICE

These instructions are intended as a supplement to the Peerless® PureFire® Installation, Operation and Maintenance Manual and are intended for use by a qualified technician.

A. Scope

PFC-850, PFC-1000 and PFC-1500 boilers are factory equipped with a 852IF interface adapter which allows external communication and control via the Modbus serial communication protocol. This document provides information about the data registers and values associated with the Modbus protocol.

• With the addition of a gateway device (stock code 54486), the control allows communication to BACnet™ MS/TP or BACnet™/IP protocols.
• Another gateway device (stock code 54487) is required to communicate with the LonWorks® protocol. Instructions for these devices are available separately.

B. Specification

Table 1: 852IF Analog Interface Specifications

C. Wiring 852IF

Figure 1 shows the wiring of the 852IF interface board on the PFC-850, PFC-1000 and PFC-1500 boiler.
The Modbus harness (PF7030) is used to connect from the J7 connector to Modbus or an approved Modbus Gateway device.

Figure 1: Wiring Schematic

COLOR
ABBREVIATION KEY

BK    BLACK
BL     BLUE
BR     BROWN
GN   GREEN
GY    GREY| OR    ORANGE
PK    PINK
PR     PURPLE
RD    RED
WH   WHITE
YE    YELLOW

 LOW VOLTAGE SIZE 16/18 AWG TYPE TW, TEEN OR TEW/AWM WIRE

120 VAC VOLTAGE SIZE 16/18 AWG TYPE TW, TFFN OR TEW/AWM WIRE

PF-850/1000/1500 WIRING TERMINALS

1. BRNR #1 POWER
2. 120V CONTROL SUPPLY
3. ALARM DRY CONTACTS
4. CASCADE LINK DEPENDENT BOILER
5. CASCADE LINK MASTER BOILER
6. MODBUS INPUT
7. 0-10V ANALOG INPUT
8. SYSTEM SENSOR

D. Modbus Address

In order to communicate with several boilers, each boiler must be given a discrete Modbus Address.

• By default, this Modbus address is 1.
• To change the Modbus address use the menu selection in the Installer menu under “Burner Settings” for “Modbus Address” right after “Cascade Address”.
• The Modbus Address may be set to any value between 0 and 254.

E. Modbus Operation

1. Holding Registers: Table 2 below shows the Modbus holding registers for the 852IF. Further tables detail potential values for some of these registers.

Table 2 – 852IF Holding Registers

Holding Register

| **Access*| Parameter Name| Conversion| Range
---|---|---|---|---
Dec.| Hex.| Read**|

Write

100

| 0064| X|

X

| Modbus Units| | 0 = °C; 1 = °F

101

| 0065|

X

| | Device Type| | 3 = Standalone PFC-850/1000/1500

102

| 0066|

X

| | State (Managing)| | See Table 3

103

| 0067|

X

| | Status (Managing)| | See Table 4

104

| 0068|

X

| | Error Code (Managing)| | See Table 5 & 6

105

| 0069|

X

| | Warning Code| | See Table 7

106

| 006A| X|

X

| CH Setpoint| Value/100= Temp| Temp is in C or F depending on Modbus Units

107

| 006B| X|

X

| DHW Setpoint| Value/100= Temp| Temp is in C or F depending on Modbus Units

108

| 006C| X|

X

| Not Applicable| | Not Applicable

109

| 006D| X|

X

| Not Applicable| | Not Applicable

110

| 006E| X|

X

| CH Mode| | Table 8

111

| 006F| X|

X

| DHW Mode| | Table 9

112

| 0070|

X

| | Supply Temperature| Value/100= Temp| Temp is in C or F depending on Modbus Units

113

| 0071|

X

| | Return Temperature| Value/100= Temp| Temp is in C or F depending on Modbus Units

114

| 0072|

X

| | DHW Temperature| Value/100= Temp| Temp is in C or F depending on Modbus Units

115

| 0073|

X

| | Flue Gas Temperature| Value/100= Temp| Temp is in C or F depending on Modbus Units

116

| 0074|

X

| | Header Temperature| Value/100= Temp| Temp is in C or F depending on Modbus Units

117

| 0075|

X

| | Firing Rate (Managing)| Auto| 0 to 100%

118

| 0076|

X

| | Not Applicable| |

119

| 0077|

X

| | Flame Current| | µA

120

| 0078|

X

| | Water Pressure| | Not Applicable

121

| 0079|

X

| | Analog In| | 0-10 VDC

122

| 007A|

X

| | Not Applicable| | Not Implemented

123

| 007B|

X

| | Not Applicable| | Not Implemented

124

| 007C|

X

| | CH Pump| | 0-100%

125

| 007D|

X

| | DHW Pump| | 0-100%

126

| 007E|

X

| | Successful Ignitions| | Value shown x 16 = Ignition Count OK

127

| 007F|

X

| | Failed Ignitions| | Value Shown = Ignition Count Failed

128

| 0080|

X

| | Flame Failures| | Value Shown = Flame Count Failed

129

| 0081|

X

| | Burner On (CH)| | Burner High Hours = Burner On Time (Hours)

130

| 0082|

X

| | Burner On (DHW)| | Burner Med Hours = Burner DHW Hours

131

| 0083|

X

| | Not Applicable| | Not Implemented

150

| 0096|

X

| | State (Dependent)| | See Table 3

151

| 0097|

X

| | Status (Dependent)| | See Table 4

152

| 0098|

X

| | Error Code (Dependent)| | See Table 5 & 6

153

| 0099|

X

| | Firing Rate (Dependent)| | 0-100%

2. Temperature Input/Output: Be sure to change the Modbus units to the appropriate value (Fahrenheit or Celsius) before reading or writing these values. When reading the values of register number 106, 107, 112, 113, 114, 115 & 116 the value must be scaled by dividing by 100. When writing the value for register numbers 106 & 107, the desired value must be multiplied by 100 before entering. This scaling is the same for both Fahrenheit and Celsius units.

• In order to write CH set point, boiler must be set to CH Mode 0 or 3.

3. Successful Ignitions: The value read from register 126 (Successful Ignitions) must be multiplied by 16 to get the actual value.

4. State & Status: The registers shown in Tables 3 & 4 give information about the current condition of the control. Note that there are “State” & “Status” values that can be read for both the Managing control and the Dependent control.

Table 3: Control State Descriptions

STATE

| State Name| Description
Dec|

Hex

0

|

0x00

| RESET_0| Initialization

1

|

0x01

| RESET_1| Initialization

2

|

0x02

| STANDBY_0| Standby waiting for heat demand

3

|

0x03

| SAFETY_ON| Ignition Sequence

4

|

0x04

| SAFETY_OFF| Ignition Sequence

5

|

0x05

| PRE_PURGE| Ignition Sequence

6

|

0x06

| PRE_PURGE_1| Ignition Sequence

7

|

0x07

| IGNIT_0| Ignition Sequence

8

|

0x08

| IGNIT_1| Ignition Sequence

9

|

0x09

| BURN_0| Following Boiler Demand

10

|

0x0A

| POST_PURGE_0| Purging Combustion Chamber

11

|

0x0B

| POST_PURGE_1| Purging Combustion Chamber

12

|

0x0C

| PUMP_CH_0| Following CH Demand w/o Heat Input

13

|

0x0D

| PUMP_CH_1| Post purge Pumping after CH Demand

14

|

0x0E

| PUMP_HW_0| Following DHW Demand w/o Heat Input

15

|

0x0F

| PUMP_HW_1| Post Purge Pumping after DHW Demand

16

|

0x10

| ALARM_1| Error Handling

17

|

0x11

| ERROR_CHECK| Error Handling

18

|

0x12

| BURNER_BOOT| Controller (re)start

19

|

0x13

| CLEAR_E2PROM_ERROR| Error Handling

20

|

0x14

| STORE_BLOCK_ERROR| Error Handling

21

|

0x15

| WAIT_A_SECOND| Error Handling
Table 4: Control State Descriptions

STATE

| State Name| Description
Dec|

Hex

0

|

0x00

| STANDBY| Standby waiting for Heat Demand

14

|

0x0E

| BLOCK| Error Handling

10

|

0x0A

| ALARM| Error Handling

15

|

0x0F

| FROST_PROTECT| Freeze Protection Demand

16

|

0x10

| CH| Central Heating Demand

17

|

0x11

| RESET_STATE| Initializing

18

|

0x12

| STORAGE| DHW Demand

19

|

0x13

| Not Applicable| Not Applicable

20

|

0x14

| Not Applicable| Not Applicable

21

|

0x15

| STORE_WARM_HOLD| DHW Demand (Store Warm Hold)

5. Error Codes: There are two types of error codes: Blocking and Lockout. Blocking errors will prevent the control from firing the burner until the condition causing the error is corrected. Lockout errors require a manual reset at the control to resume normal boiler operation. Table 5 (below) lists Lockout error codes and their descriptions. Table 6 lists Blocking error codes and their descriptions.

Table 5: ERROR_NUMBER (Lockout Errors)

Error Number

| Error Description| Display Code
Dec|

Hex

1

|

0x01

| Fan Speed Error – Incorrect fan speed for more than 60 seconds|

A33

2

|

0x02

| Ignition Error – 3 consecutive failed ignition attempts|

A01

5

|

0x05

| Internal Control Error – Gas Valve Relay Error|

A04

6

|

0x06

| Internal Control Error – Safety Relay Error|

A06

9

|

0x09

| Internal Control Error – RAM Error|

A09

10

|

0x0A

| Internal Control Error – E2PROM Out of Date|

A12

11

|

0x0B

| Boiler Return Temperature Higher than Supply|

A50

12

|

0x0C

| Internal Control Error – Communication Error E2PROM|

A10

13

|

0x0D

| Internal Control Error – State Error|

A13

14

|

0x0E

| Internal Control Error – ROM Error|

A14

15

|

0x0F

| Internal Control Error – Air Switch Not Open|

A21

16

|

0x10

| Internal Control Error – 15MS XRL Error|

A15

17

|

0x11

| Internal Control Error – Air Switch Not Closed|

A22

18

|

0x12

| High Temperature Limit Open|

A03

19

|

0x13

| Internal Control Error – Stack Error|

A18

20

|

0x14

| Flame Detected After Shutdown|

A19

21

|

0x15

| Flame Detected Before Ignition|

A20

22

|

0x16

| Internal Control Error – 20MS XRL Error|

A16

23

|

0x17

| Internal Control Error – 41MS Error|

A32

24

|

0x18

| Flame Failure – 3 failures during one heat call|

A02

25

|

0x19

| Flow Switch Open / Circulator Off|

A23

26

|

0x1A

| Flow Switch Closed / Circulator On|

A24

27

|

0x1B

| Internal Control Error – Flag Byte Integrity Error|

A09

28

|

0x1C

| Internal Control Error – AD HI CPL Error|

A09

29

|

0x1D

| Internal Control Error – AD LO CPL Error|

A09

30

|

0x1E

| Internal Control Error – Register Error|

A09

Table 6: ERROR_NUMBER (Blocking Errors)

Error Number

| Error Description| Display Code
Dec|

Hex

31

|

0x1F

| Internal Control Error – REFHI Too Low Error|

E45

32|

0x20

| Internal Control Error – REFHI Too High Error|

E46

33|

0x21

| Internal Control Error – REFLO Too Low Error|

E47

34|

0x22

| Internal Control Error – REFLO Too High Error|

E48

35|

0x23

| Unexpected Flame Detected|

E20

36|

0x24

| Interlocks Open – Gas Press, LWCO or External|

E31

39|

0x27

| High Exhaust Vent Temperature (>194°F; >90°C)|

E30

40|

0x28

| High Return Temperature|

E32

41|

0x29

| Blocked Condensate Drain|

E26

43|

0x2B

| Poor Ground Connection|

E24

44|

0x2C

| Hot & Neutral Legs Reversed|

E21

45|

0x2D

| Frequency Error|

E23

46|

0x2E

| Poor Ground Connection|

E24

47|

0x2F

| Internal Control Error – WD Comm Error|

E42

51|

0X33

| Supply Sensor Not Connected|

E01

52|

0X34

| Return Sensor Not Connected|

E02

55|

0X37

| DHW Sensor Not Connected|

E04

57|

0X39

| Flue Sensor Not Connected|

E05

59|

0X3B

| Supply Sensor Shorted|

E11

60|

0X3C

| Return Sensor Shorted|

E12

63|

0X3F

| DHW Sensor Shorted|

E14

65|

0X41

| Flue Sensor Shorted|

E13

66|

0X42

| Reset Button Error (Activated 7 times in 1 minute)|

E51

67|

0X43

| Flap Not Closed|

E52

68|

0X44

| Flap Not Open|

E53

6. Warning Errors: Table 7 shows values for warning codes. Warnings are associated with temperature sensors that are either shorted or open. At the boiler these errors are indicated by a flashing burner control displays (in the electrical enclosure on the boiler).

Table 7: WARNING_NUMBER

Warning Number

| Error Description| Display Code
Dec|

Hex

1

|

0x01

| Outdoor Sensor Shorted|

W01

2|

0x02

| DHW Sensor Not Connected|

W02

3|

0x03

| DHW Sensor Shorted|

W03

4|

0x04

| Flue Sensor Not Connected|

W04

255|

0xFF

| All Sensors Operating Correctly|

7. CH & DHW Mode: Table 8 shows register values for central heating (CH) modes. These values are typically set upon commissioning based on the piping configuration. Table 9 shows the values for domestic hot water (DHW) modes. Again, these values are dependent on the piping and wiring configuration.

Table 8: CH Mode

CH Mode Number

| CH Mode Description| Description
Dec|

Hex

0

|

0x00

| Indoor Thermostat| Boiler maintains a fixed, user-defined, temperature setpoint
Boiler responds to thermostat demand targeting temperature setpoint

1

|

0x01

| Thermostat and Outdoor Reset| Boiler temperature is calculated based on outdoor temperature
Boiler responds to thermostat demand targeting the calculated temperature

2

|

0x02

| Full Outdoor Reset| Boiler temperature is calculated based on outdoor temperature
Boiler maintains targeted temperature calculated by the control with no thermostat input
Closure of terminals #1 & #2 causes a temperature setback of 18°F

3

|

0x03

| Permanent Demand| Boiler maintains a fixed, user-defined, temperature setpoint
Boiler maintains the fixed temperature setpoint with no thermostat input
Closure of terminals #1 & #2 causes a temperature setback of 18°F

4

|

0x04

| 0-10 V Input to modulate setpoint| Boiler starts if analog voltage is above 1.5 VDC
Boiler temperature corresponds to an external analog input between 2 VDC (68° F) and 10 VDC (195° F)

5

|

0x05

| Not Applicable|

6

|

0x06

| Hydro-Air Unit| Boiler maintains a fixed, user-defined, temperature setpoint
Boiler responds to thermostat demand targeting temperature setpoint
Table 9: DHW Mode

DHW Mode Number

| DHW Mode Description| Description
Dec|

Hex

0

|

0x00

| No DHW| No indirect hot water tank is connected
Boiler will not respond to any input on terminals #5 & #6

1

|

0x01

| DHW store with sensor| Indirect hot water tank is piped in the system and a tank sensor is used
Boiler monitors indirect tank temperature using sensor input on terminals #5 &

6

2

|

0x02

| DHW store with thermostat| Indirect hot water tank is piped in the system and a thermostat is used to monitor the tank temperature
Boiler responds to DHW call for heat when the circuit is made between terminals #5 & #6

PB HEAT, LLC
131 S. CHURCH STREET • BALLY, PA 19503

©2023 PB Heat, LLC. All rights reserved.

PF8215 R1 (05/23)
Printed in U.S.A

References

• PB Heat: Peerless® Boilers - America's BEST Built Boiler

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