Error Check; Header And Trailer (Silent Interval) - Hitachi L200 Series Instruction Manual

Data:
• A function command is set here.
• The data format used in the L200 series is corresponding to the Modbus data format
below.
Name of Data
Coil
Holding Register
Function code:
Specify a function you want to make the inverter execute. Function codes available to the
L200 series are listed below.
Function
Function
Code
0 1 h Read Coil Status
0 3 h Read Holding Register
0 5 h Write in Coil
0 6 h Write in Holding Register
0 8 h Loopback Test
0 F h Write in Coils
1 0 h Write in Registers

Error check:

Modbus-RTU uses CRC (Cyclic Redundancy Check) for error checking.
• The CRC code is 16-bit data that is generated for 8-bit blocks of arbitrary length.
• The CRC code is generated by a generator polynomial CRC-16 (X16+ X15+ X2+ 1).

Header and trailer (silent interval):

Latency is the time between the reception of a query from the master and transmission of
a response from the inverter.
• 3.5 characters (24 bits) are always required for latency time. If the latency time shorter
than 3.5 characters, the inverter returns no response.
• The actual transmission latency time is the sum of silent interval (3.5 characters long)
+ C078 (transmission latency time).
Binary data that can be referenced and changed (1 bit long)
16-bit data that can be referenced and changed
Maximum data size
(bytes available per
message)
L200 Inverter
Description
Maximum number of
data elements available
per message
4 32 coils (in bits)
4 4 registers (in bytes)
1 1 coil (in bits)
1 1registers (in bytes)
—
4 32 coils (in bits)
4 4 registers (in bytes)
B–7
—