Micro820 communication with Solo Temp controller

[Spidermite]

I am trying to use a Micro820 to communicate with a Solo SL4896VRE
temperature controller. The Solo came from Automation Direct.

physical connections between the 2 are:
Micro820 D+ to Solo D+
Micro820 D- to Solo D-

The temperature controller is set up as follows:
C-SL (Modbus Protocol) rtu
C-no (Network Address) 1
bps 9600
LEn 8
Prty Even
Stop 1

The Micro820 controller serial settings are:
Driver ModbusRTU
Baud Rate 9600
Parity Even
Modbus Role Master (but have tryed Auto also)
Protocol Control
Media RS485
Data Bits 8
Stop Bits 1
Responder Timer 200ms
Broadcast Pause 200ms
Inter-Frame 0 Us
(Delay/Timeout)

The Solo documentation states that the set point is at location 44098
I have included 2 attachments. One is a screen shot of the variables used
and the other is the one rung that is the program.





Once the program is downloaded and I force the trigger, I expect
the Local_Add registers to become populated. All I get are 0's

What am I not doing?

 

[danw]

A Total wild guess:

Target_Add.Addr is 44098

The leading numeral 4 is indicates that the data is in a Holding Register. It is not part of the indexed register address, it is not part of the Modbus message. It is an indicator for the location of the register address.

The actual address is 1001 (hex) or 4098 decimal. 1001H = 4097, but hex address start at 0000, but decimal registers start at 0001, so decimal addresses are one higher than hex.

Try 4098.

That assumes that somewhere else in all that cryptic programming that you said that the Modbus Function Code (FC) is 03. FC 03 deals with registers in the Holding Register area.

Sometimes masters use the leading numeral (whatever it is) to determine which memory area the register address is associated with.

I generally do a read operation before I do a write operation because it confirms the hardware and the addressing scheme.

 

[Spidermite]

I'll bet you are right. I will try address 4098 at work tonight. I thought that 44098 seemed a little funny. This is my first attempt at anything modbus. Thanks for the suggestion!

Don

 

[Spidermite]

Yup, that was it. I punched in a bunch locations without that leading "4" and was able to read a bunch of data. Thank you very much.

Don