10
LEAD/LAG CONTROL OPTION 3:
The EMS performs lead-lag and outdoor reset function by communicating with the TempTrac
®
control through MODBUS
serial protocol. The TempTrac
®
can be equipped with a TTL to RS485 adapter. In this case the EMS system will directly
adjust the operating set point of each EMBLEM
®
boiler system in order to achieve the desired loop temperature as well
as designating lead-lag preference. The following is an example of this interface:
Typical “Two-Wire” Solution
WRITE SINGLE REGISTER (0x06):
Slave Address
: Defines the device address that receives the communication data.
Function Code
: Code of the desired function = 0X06
Register Address
: The address of the first register to be read. Set point 1 (St1) has a register address of 768
Data:
The data to write
CRC
: Defines the CRC calculated for the frame data received and has to be used to verify the integrity of data received.
The answer message is an echo of the command you sent (it has the same format).
See the TempTrac
®
MODBUS-RTU Manual (34-502), for addition information on communication protocol.
Riverside Hydronics
®
, LLC - 990 Haltom Road - Fort Worth, Texas 76117 - Tel 1-800-990-5918
Slave
Address
Function
Code
Register
Address
(MSByte)
Register
Address
(LSByte)
Data
(MSByte)
Data
(LSByte)
CRC
(LSByte)
CRC
(MSByte)
Master
Temp
Trac
®
Temp
Trac
®
D0
D1
COMMON
L
L
-
+
TXD0&RXD0
TXD1& RXD1
-
+
PULL
DOWN
PULL
UP
XJ485 SERIAL INTERFACE
