MEMORY MAP
Synergy Modbus communication is based on reading or writing equipment parameters from or to the holding registers. The data
addressing is zero offset such that the parameter number corresponds to the register number.
Parameter Number (PNU)
Modbus Data Address
Decimal
Hexadecimal
PNU0000
0
0000h
PNU0001
1
0001h
:
:
:
:
:
:
PNU0128
128
0080h
:
:
:
:
:
:
MESSAGE TIMING
In the RTU mode there is no specific start or stop byte that marks the beginning or the end of a telegram. Indication of when a
new message begins or when it ends is achieved by the absence of data transmission for a minimum period of 3.5 times the
transmission time of a data byte. Thus, in case a telegram is transmitted after this minimum time has elapsed; the network
elements will assume that the first received character represents the beginning of a new telegram.
T
11 bits
= Time for transmitting one byte of the telegram.
T
between bytes
= Time between bytes.
T
3,5x
= Minimum interval to indicate beginning and end
of a telegram (3.5 x T11bits).
Telegram
T
3.5x
T
interval
T
3.5x
T
11 bits
MAN-SGY-012-V11 EC 5195
Fairford Electronics Ltd - Synergy Modbus RTU Programming Manual - 22nd February 2016
Page 6 of 59