Pilot Communications SPM33 User Manual

6) Under any circumstance, Slave can just respond one request.
8.2.2. Modes of Transmission
MODBUS protocol supports ASCII and RTU modes of transmissions. The
SPM33 supports only the RTU mode of transmission with 8 data bits, no parity,
and one stop bit.
8.2.3. Description of the Modbus Packet Structure
Every MODBUS packet consists of four fields:
1) The Address Field
2) The Function Field
3) The Data Field
4) The Error Check field
z Address Field
The address field is 1-byte long and identifies which slave device the
packet is for. Valid addresses range between 1 and 247. The slave device
whose address matches the value in this field will perform the command
specified in the packet.
z Function Field
The function field is 1-byte long and tells the addressed salve which function to
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Pilot Communications SPM33 Specifications

General

Brand	Pilot Communications
Model	SPM33
Category	Measuring Instruments
Language	English