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Table Of Contents

S7810M MODBUS™ MODULE

5 65-0249—07

Table 3. Query Message Format for Function Codes 3 and 4.

Table 4. Response Message Format for Function Codes 3 and 4.

Table 5. Query Message Format for Function Code 6 (Broadcast is supported by using a slave address of 00).

Table 6. Response Message Format for Function Code 6 (There is no response if the query was broadcast.)

Table 7. Query Message Format for Function Code 17.

NOTE: See Table 20 for function code 17 response format.

Table 8. Exception Response Message Format.

Table 9. Exception Codes.

Device Address and Baud Rate

Assign each S7810M in the system a unique address by

setting the MODBUS ADDRESS switches on the bottom of the

device to the correct number. See Fig. 4. Only RTU

communications with 1 Start Bit, 8 Data Bits, 1 Stop Bit and no

parity is supported.

NOTE: Assign a device address number from 01 to 99. 00 is

not an acceptable address number and will not work.

The default baud rate is 9600. To change the baud rate to 19.2K,

use a needlenose pliers to remove the jumper. See Fig. 4.

IMPORTANT:

S7999B requires a baud rate of 19.2K.

Fig. 4. 7810M Address Switches and Baud Rate Jumper.

NOTE: In Tables 10, 15 and 19: Line 1 and Line 2 refer to the

two lines of text on the S7800 Keyboard Display Mod-

ule. In Tables 15, 17 and 19: The String Code column

references Table 16, String Codes. In Table 15: The

Burner Control State Bits column references Table 22,

Burner Control State Bits.

Slave Address

Function

Code

Starting

Address High

Starting

Address Low

Number of

Addresses High

Number of

Addresses Low CRC CRC

01 03 00 0A 00 01 A4 08

Slave Address Function Code Byte Count Data High Data Low CRC CRC

01 03 02 00 22 38 5D

Slave

Address

Function

Code

Starting

Address High

Starting

Address Low

Preset Data

High

Preset Data

Low CRC CRC

01 06 00 7F 00 04 B9 D1

Slave

Address

Function

Code

Starting

Address High

Starting

Address Low

Preset Data

High

Preset Data

Low CRC CRC

01 06 00 7F 00 04 B9 D1

Slave

Address

Function

Code CRC CRC

03 11 C1 4C

Slave

Address

Function

Code

+ 80h

Exception

Code

CRC CRC

Exception

Code Definition Description

01 Illegal

Function

An illegal function as requested.

Only 3, 4, 6 and 17 are supported.

02 Illegal Data

Address

Too many bytes requested, address

is out of range, register is read only,

or the number of address requested

is past the last register.

03 Illegal Data

Value

The “Preset Data” from function

code 6 is invalid/out of range.

10'S 1'S

BAUD

RATE

MODBUS

ADDRESS

OUT

19.2K

9600

SCREWDRIVER

NEEDLENOSE

PLIERS

M17650