Contemporary Control Systems Modbus Cube I/O MR-AI8 User Manual

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Continuation Software Description

Example for a frame:

Slave address

0x12 Setting of rotary switch (18)

Function

0x06 Write Single Register

0x00

0x41 Bit rate and parity (65)

All devices can be switched simultaneously with a Broadcast com-

mand (Slave address 0x00) However, it is advised not to do so as

this can cause problems:

- Devices from other manufacturers may have under this

address a register for a different purpose that will then be

operated in the wrong way.
- There is no feedback from the individual devices.

Consequently the control cannot immediately recognize if

the command was correctly received.

It is safer to address and switch each device individually.
The device will then answer with the old settings of parity and

bit rate. Switching will take place only afterwards. However, the

answer can get lost if the bus is disturbed.
When all devices are switched; it is advised to check communica-

tion. Any function of the device providing a feedback is suitable.

If a single function is to be used being independent from the

process periphery then the function „Diagnostic“ sub-function

„Return Query Data“ is suitable, it returns the transferred data.
If bit rate and parity setting of a device are unknown it is possible

to address the device successively with all combinations of bit

rate and parity until the device answers. Try the most likely

combinations first. Try the lower bit rates last as they take longer.

10.3 General Commands

“08 (0x08) Diagnostics”
Subfunction “0 ( 0x0000) Return Query Data”

Data Field Any
Response: Echo of Request

Subfunction “1 (0x0001) Restart Communication Option”

Data Field 0x0000 or 0xFF00
Response: Echo of Request
Action: Clears all Error Counters, Restarts node

Subfunction “4 (0x0004) Force Listen Only Mode”

Data Field 0x0000
No Response
Action: No response until Node Reset or Function

Code 08 Subcode 01

Subfunction “10 ( 0x000A) Clear Counters”

Data Field 0x0000
Response: Echo of Request
Action: Clears all Error Counters

Subfunction “11 ( 0x000B) Return Bus Message Count”

Data Field 0x0000
Response: Quantity of messages that the remote device has

detected on the communications system since its last restart,

clear counters operation, or power–up.

Subfunction “12 ( 0x000C) Return Bus Communication Error

Count”

Data Field 0x0000
Response: Quantity of errors encountered by the remote

device since its last restart, clear counters operation,

or power–up. (CRC, Length <3, Parity, Frame)

Continuation Software Description

Subfunction “13 ( 0x000D) Return Bus Exception Error Count”

Data Field 0x0000
Response: Quantity of MODBUS exception responses returned

by the remote device since its last restart, clear counters

operation, or power–up.

Subfunction “14 (0x000E) Return Slave Message Count”

Data Field 0x0000
Response: quantity of messages addressed to the remote

device, or broadcast, that the remote device has processed

since its last restart, clear counters operation, or power–up.

Subfunction “15 (0x000F) Return Slave No Response Count”

Data Field 0x0000
Response: Quantity of messages addressed to the remote

device for which it has returned no response (neither a normal

response nor an exception response), since its last restart, clear

counters operation, or power–up.

“43 /14 (0x2B / 0x0E) Read Device Identification”
Request

Read Device ID code: 0x01
Object ID 0x00

Response

Device ID code 0x01
Conformity level 0x01
More follows 0x00
Next object ID 0x00
Number of objects

0x03

Object ID 0x00
Object Length 0x03
Object Value “BTR”
Object ID 0x01
Object Length 0x06
Object Value “MR-AI8”
Object ID 0x02
Object Length 0x04
Object Value “V1.0”

This manual is related to the following products:

Modbus Cube I/O MR-DI4 Modbus Cube I/O MR-DO4 Modbus Cube I/O MR-DI10 Modbus Cube I/O MR-DIO4/2