−27−
6.5.7 Loop back test
[Function code: 08 (08H)]
Check transmission between master and slave units. Response is made according to a specified
diagnosis code. With the diagnosis code fixed at “0000H”, the LT830 controller performs a “return
check” of unaltered received data transmissions.
Example) Executing “Loop back test” on the slave unit 2.
(RTU mode)
Master
→
Instruments Instruments
→
Master (normal)
Slave address
02H
Slave address
02H
Function code
08H
Function code
08H
Diagnosis code (H)
00H
Diagnosis code (H)
00H
Diagnosis code (L)
Fixed
00H
Diagnosis code (L)
Fixed
00H
Arbitrary data
∗
Received data
∗
Arbitrary data
∗
Received data
∗
CRC (L)
∗
CRC (L)
∗
CRC (H)
∗
CRC (H)
∗
6.5.8 Write multiple analog parameters (Change multiple coils status)
[Function code: 15 (0FH)]
According to the specified number, programs the specified number of digital parameters into the
specified status (OFF or ON). Every 8 specified numbers which are OFF or ON form a single data unit
(byte). The LSB of each data unit (D0) is the digital data of the smallest numbered data. When the
number of specified numbers is not a multiple of 8, the unnecessary bits are ignored.
Example) Executing the AT on the slave unit 2.
(Program the data of the digital parameters with reference numbers 101 of the slave unit 2
as shown below.)
Reference No.
101
Data ON
AT
start
(RTU mode)
Master
→
Instruments Instruments
→
Master (normal)
Slave address
02H
Slave address
02H
Function code
0FH
Function code
0FH
Start No. (H)
00H
Start No. (H)
00H
Start No. (L)
64H
Start No. (L)
64H
Number of Reference No. (H)
00H
Number of Reference No. (H)
00H
Number of Reference No. (L)
01H
Number of Reference No. (L)
01H
Number of data
01H
CRC (L)
D5H
1st 8 data 01H
CRC
(H) E7H
CRC (L)
DEH
CRC (H)
8AH
LRC 88H
LRC 8AH
Note) Start No. (Relative value) is given by “Reference No. – 1”. (Decimal number 100 (=101 – 1)
Hexadecimal 64H)
Note) When the slave address is programmed to “0”, all the slave units execute this command,
although no response is received from any of them.
Note) The number of message data transmittable (receivable by this controller) at one time is limited.
(See Section 6.4)
(Error check in ASCII mode)