Modbus TotalFlow

Hi everyone,
I have an issue with my TotalFlow xrc6490.
I have com1 rs232 slave rtu where it's working properly and com2 rs485 host rtu communicating with solar plc.
I used modbuspoll and i receive on register
40001= 17290, 40002= 3144, 40003= 16502
These values are correct from solar plc and it changes each 1 sec as configuring on mrb file (interval 1sec). but when i use the solar plc with totalflow i receive on
40001= 16384, 40002= 2154, 40003= 512... with no change.
The configuration is correct on R:/com2/modbus/solar.mrb and there is no communication error on the com2 stastics.
I use on holding register capacity 8 int16 and the mrb file int16 with 400257 is 9.6.0, 9.6.1....

NB: on the mrb.png the type of register is not a float but int16.

I hope you could help me because i am blocked.

Regards,
Dino

Most likely you have an address error or an error with what you are reading. For instance address 40000 could be flags. Check out: https://en.wikipedia.org/wiki/Modbus

To troubleshoot you need to hook up your computer so you can see what is sent and what is received between master and slave.
Then it's pretty easy to figure out what is the problem. Otherwise you have to check and double check.

Another thing you can try is to set up your computer to be a modbus slave.
Then you can feed values to your PLC and check that you receive the right values.

.

Hi Pete.S,
Thanks for your reply, I'll check and back to you.
Dino

do you have the totalflow set for totalflow modbus or modicon modbus? the difference is totalflow modbus uses 32 bit registers or enron modbus and the modicon is standard 16 bit modbus.

It's 16 bit modicon as shown on the png. I tried everything 16 bit, 32.... But nothing. Before Use the xrc the communication was working properly with the old PLC who was arcom. But when i replaced it with the xrc com2 doesnt work.

what is the datatype in the solar plc? I am not familiar with that type of plc at all. if it is an int, does it supply the data as a signed or unsigned int?

The solar PLC is enerpac regulator and on the old PLC arcom the modbus table it's signed registers started by 40001 and it worked properly also when i tried modbus poll I received on 40001 thé right value who is changing each seconde and with the xrc it is fixed 16384 on 40001 register.

You're all over the map. I can't figure out what is what and who talks to whom.

Some observations and comments:

1) You mention 5 devices
- TotalFlow xrc6490
- slave rt tu (com1rs232)
- com2 rs485 host rtu
- solar plc
- old plc arcom

Which device is communicating with which?
Which combinations work with each other?
Which device works with Modpoll, which device does not?

Which combinations do not work with each other?
Which device does not work with Modpoll, which device does not?

Is a 'host' a Modbus master?

Is the solar PLC a modbus master or slave?

Is the TotalFlow xrc6490 a Modbus master or Modbus slave?

2) number formats

a) What kind of number has 3 decimal points? 9.6.0 I have no idea what 9.6.0 is.

A floating point number has one decimal point and a "floating" number of digits to the right of the decimal point, for instance,
23.36267523
1.78
457111.32

b) >on the old PLC arcom the modbus table it's signed registers
Registers hold date values. Registers are not signed or unsigned. The data values in a register might be signed integers or unsigned integers. If you do not mean signed integers, what do you mean by 'signed registers'?

3) > also when i tried modbus poll I received on 40001 thé right value

Did Modbus poll (Modpoll?) sucessfully talk to com 2? Does com 2 work with Modpoll, but not work with whatever the other device is?

I'll explain
Arcom PLC has been replaced by xrc6490 witch is well RTU application.
There are two comms com1 slave RTU to DCS who is working properly with serial rs232 16 bit modicon. The com2 is master RTU communicating with enerpac solar PLC with serial rs485 16 bit modicon who is not working.
On the png you can see the mrb file with function 3 address 1 for slave and starting register 40001 to register 9.6.0 witch is 16int type.

I used with my laptop modbus poll with solar PLC and I received a right valuen on 40001, 40002... I'll use modbus slave simulator with com2 and try to send value to xrc and see what I'll read and back to you

what is the datatype that you are trying to read in the solar plc?

Have you tried offsetting your address by 1? thats typical with modbus.

this should be simple if it is an int. I see in your mrb you have the datatype set to float. make sure that this is int or the totalflow may try to convert the int to a float and then split it into 2 registers.

I also wonder if having the spaces between the totalflow registers may be causing problems. maybe you should assign a totalflow register to those blank spots also.

I would prob just setup 1 register and adjust the settings until I find the issue. then start adding more.

sorry I cant be more help, I havent fooled with modbus master on a totalflow in quite a while.

I rectify on mrb it's int16, it was an old image of mrb. Slave address is 1 not 0, just for my tests i put 0.
please find attached an image with setting

I would change # registers to 1 and then try and change the starting register to 40000 or 40002 just to see if you get the proper value for what should be 40001 on the plc.

diat150 said:

I would change # registers to 1 and then try and change the starting register to 40000 or 40002 just to see if you get the proper value for what should be 40001 on the plc.

Click to expand...

I assume your correctly setting the MSB or LSB in the Solar PLC? Diat is probably on to something as some plc's let you only read a specific number of registers, so try looking at getting one only to read.
Keep us informed!

Hi All,
Finally it works and I want to thank you all .
I put only 1 register on the mrb file 9.6.0 and the communication has been established but when I add a seconde one it blocks. Do you have any idea to add the others registers or I have to create another mrb file for each register?
a waiting for your reply