I would really like to find out what I'm doing wrong by trying to accomplish this. Here's where I'm at...

SOLO 4848 Temp Controller with comm settings as follows:

CoSH = on

C-SL = rtU

C-no = 2

bPS = 9600

LEn = 8

Prty = EvEn

StoP = 1

In the Productivity Hardware configuration under the CPU for Serial ports (RS-485 port) I have:

Port Name = CPU-485

Port Security = Read/Write

Protocol = Modbus RTU

Baud Rate = 9600

Node Address = 1

Parity = Even

Data Bits = 8

Stop Bits = 1

Timeout = 5 x 100 msec

For the Modbus Read Instruction I have:

Serial Port CPU-485

Slave Node Number 2

Automatic Polling 100 / 0

Don't Skip Exec.

No Word Swap

No 32 Bit Data to 16 Bit Mapping

Slave Modbus Start Address 4097

Modbus Decimal Addressing

Modbus Function Code 3: Read Holding Registers

Non-Array Tag that I named Temp_PV

Wiring:

RS-485 + terminal goes to SOLO terminal 9

RS-485 - terminal goes to SOLO terminal 10

I do see the lights flicker. The Rx light stays on most of the time but flickers off now and then. The Tx light is off most of the time but flickers on now and then. I also have a Write Instruction with all the same settings as the read except the start address is 4098 and Function Code 6: Write Single Register and the tag name is Temp_SV.

I set a couple rungs using the Read Error and Write Error bits to turn on latching output relays but they aren't coming on so I'm assuming there are no errors.

Has anyone done this?