Function Codes - Spirax Sarco VLM20 Instrucciones De Instalación Y Mantenimiento

5.5.12 Orden Modbus
The Modbus RTU protocol is supported in this implementation. Supported baud rates are 1200,
2400, 4800, 9600, 19200, 38400, 57600, and 115200. The default baud rate is 19200 baud.
Depending upon the Modbus protocol selected, data are transmitted in 8-bit data frames with
even or odd parity and 1 stop bit, or no parity and 2 or 1 (non-standard) stop bits.
The current Modbus protocol specification does not define register usage, but there is an informal
register numbering convention derived from the original (now obsolete) Modicon Modbus protocol
specification, and used by many vendors of Modbus capable products.
Registers Usage
00001-09999 Read/write bits ("coils")
10001-19999
Read-only bits ("discrete inputs")
Read-only 16 bit registers
("inputregisters"), IEEE 754 floating point
30001-39999 register pairs, arbitrary length strings
encoded as two ASCII characters per 16-
bit register
Read/write 16-bit registers ("holding
registers"), IEEE 754 floating point register
40001-49999
pairs, arbitrary length strings encoded as
two ASCII characters per 16- bit register
Each range of register numbers maps to a unique range of addresses that are determined by the
function code and the register number. The address is equal to the least significant four digits of
the register number minus one, as shown in the following table.
Registers

Function codes

00001-09999 01, 05, 15
10001-19999 02
30001-39999 03, 04
40001-49999
03, 06, 16
92
Valid function codes
01 (read coils)
05 (write single coil)
15 (write multiple coils)
02 (read discrete inputs)
03 (read holding registers) 04
(read input registers)
03 (read holding registers)
6 (write single register)
16 (write multiple registers)
Data type and address range
Read/write bits 0000-9998
Read-only bits 0000-9999
Read-only 16-bit registers 0000-9998
Read/write 16-bit registers 0000-9998
IM-P339-06 MI Issue 2