Hitachi L2002 Data:, Error check:, Function code:, Header and trailer (silent interval):

B–7

L2002 Inverter

Data:

•A function command is set here.

•The data format used in the L2002 series is corresponding to the Modbus data format below.

Name of Data	Description
Coil	Binary data that can be referenced and changed (1 bit long)
Holding Register	16-bit data that can be referenced and changed

Function code:

Specify a function you want to make the inverter execute. Function codes available to the L2002 series are listed below.

Function		Maximum data size	Maximum number of
	Function	(bytes available per	data elements available
Code
		message)	per message
0 1 h	Read Coil Status	4	32 coils (in bits)
0 3 h	Read Holding Register	4	4 registers (in bytes)
0 5 h	Write in Coil	1	1 coil (in bits)
0 6 h	Write in Holding Register	1	1registers (in bytes)
0 8 h	Loopback Test	—	—
0 F h	Write in Coils	4	32 coils (in bits)
1 0 h	Write in Registers	4	4 registers (in bytes)

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).

B Appendix