Modbus RS485
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Modbus RS485 Interface
Operating Guide
Modbus RS485
Function Code Type Function
3
Read Holding
Register
Reads one or more registers of the MXD70 Series.
1 to a maximum of 125 consecutive registers
(1 register = 2 bytes) can be read with a telegram.
Application: For reading measurements and the
configuration of the instrument’s parameters.
5
Write Single Coil Writes a single output to either ON or OFF in the MXD70
Series.
The requested ON/OFF state is specified by the following
data field:
FF 00 hex = ON.
00 00 hex = OFF.
All other values are illegal and will not affect the output.
Application: Activates a single function in the MXD70
Series by writing the On state to the coil address once.
Note, on completion the function will automatically
move to the Off state.
6
Write Single Register Write a single MXD70 Series register with a new value.
Application: For configuring a single parameter in the
instrument.
! Note. Registers whose address space consume more
than one register i.e. Floats, cannot be set using this
function code.
16
Write Multiple
Registers
Writes several MXD70 Series registers with a new value.
A maximum of 120 consecutive registers can be written
with a single telegram.
Application: For configuring parameters in the
instrument.
23
Read & Write Multiple
Registers
Simultaneous reading and writing of registers in the
MXD70 Series.
1 to a maximum of 118 registers in a single telegram.
Write access is executed before read access.
Application: For configuring and then checking the
status of the parameters in the instrument.
! Maximum number of writes - If a non-volatile parameter is modified via the MODBUS this change is
saved in the EEPROM of the instrument. The number of writes to the EEPROM is technically restricted
to a maximum of 1 million. Attention must be paid to this limit since, if exceeded, it results in data loss
and instrument failure. For this reason, avoid constantly writing non-volatile instrument parameters via
the MODBUS.
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