Vijeo Cİtect V7.3 Modbus Communication Problem

[Anonymous user]

Hii Everyone,

I have to read some information via modbus. I cannot read the ULONG type data. 

Its already added 40000 and I know the issue PLC addresses (base 1)

Citect can read read couple of value (INT, UINT, or LONG type of data) but  I cannot read ULONG type of data.

Sorry For Bad English 🙂

THX.

[RobertSanders · Accepted solution]

Hi

Below is an extract from the Modbus help (attached), try the following parameters using the Setup Editor,  ensure the change is made on the IOServer. 

Note: This parameter is not applicable if you are using the protocol variant MODBUS20 or MODBUS30 to communicate with a device. Under these circumstances, a value of 3 will be hardcoded for this parameter in the driver.

[MODBUS]LongDataType

In the Modbus protocol, LONG data types defaultto a simplified implementation, with a shortened range of 0 to 99,999,999 - mode 0. Mode 2 has the samerange as mode 0, but with the register order swapped. Mode 1 supports thecomplete LONG range of -2,147,483,648 to +2,147,483,647. Mode 3 has the samerange as mode 1, but with the register order swapped.

Allowable Values: 0 to 3, where:

0 = 10000 x low register + high register
1 = 65536 x low register + high register
2 = 10000 x high register + low register
3 = 65536 x high register + low register

Default Value: 3

With this parameter, you can set different values for specific I/O devices or groups of I/O devices. See Device/group-specific parameters.

If this doesn't work we will need more information Eg what controller are you using?

Regards

Rob

[Anonymous user]

Hi

Thank you for your reply.

i tried your explanation and i read the device with modbus poll program.

read the device with LONG type and I calculate the value for 0,1,2,3 type of value. It has to be 3.

I have moxa gateway Its communicate via TCP/IP but Its has 2 diffrent serial port. Computer sees like a serial port. (COM21,22).

also Inittype has to be 3. I checked from your file(modbus help).

Here is My configuration

! #CSE:UserItem#
[MODBUS]
#Set to '3' by XXXX on 15/11/2013 13:10:58.
InitType = 3
#Set to '3' by XXXX on 16/11/2013 23:46:49.
LongDataType = 3
#Set to '64' by XXXX on 15/11/2013 13:12:15.
MaxBits = 64

Im trying to read micom p127 phase to neutral value. Data type showing ULONG type.

Citect reading other LONG type of value. for ULONG can not.

[RobertSanders]

I do not have a MiCOM P127 and are therefore unable to test with Citect. Citect SCADA has approximately 20 different Protocol configurations for Modbus Eg, Modbus1, Modbus20 in which the major parameters are hard coded into the Driver.

Check that the Citect I/O Device Protocol is set to Modbus, not Eg Modbus20, this means the parameter changes in the INI file will have an effect, unfortunately it’s a matter of trying different parameter combinations.

It may also be worth plugging the MiCOM directly into the PC using a USB to Serial converter and using a utility like ModScan to validate the readings.

Regards

Rob

[Anonymous user]

I tried to read mb poll.

Its reading value LONG type data. Also I tried to read with LONG data type in citect. It didnt work.