PLC to HART Gateway, Help Troubleshooting!

Hello,

My goal is to have a micrologix 1400 plc read data from a Hart gateway HRT-710. so I can read flow and totalizer and display them on HMI.

Here is the link to the manual: link

We have 3 other sites that are identical to this new site. I used all same programming for the PLC, flow meter (flowmag50W) and Hart gateway (HRT-710).

The only difference is the new site has only one flow meter instead of 2 flowmeters, for that reason, I made sure to select point to point inside the hart modem (HRT -710).

I proved that the HART 710 gateway is not defective by swapping with a unit from a different site.

I can read flow data and totalizer data from the flow meter via hart using the HRT-710 modem software configuration, and using PC based software(Modbus master tool) but this was accomplished by using the RS 232 on the HRT 710. note that the HRT 710 has RS 232 and RS 485 to communicate, but only one can be used at the time.

When the PLC tries to retrieve data from the HRT 710 using a message instruction, it doesn't work. Message keeps saying error 37 " time out in local processor. this PLC programming is the same as other sites.

On the Modbus side, I also have one VFD that is communicating perfectly to the PLC, But not the hart modem?... I'm using 400 ohms resister for termination on both sides, I tried 250 ohms but didn't make a difference.

Also, the baud rate is same on all slaves and master.
Baudrate:19200
Parity: none
Stop bit:1
data bit: 8
And HART modem hart 710 is using net ID 3, PLC message instruction to pool the modem is using that same net ID 3.
and cable runs are very short (Twisted pair).

-I program the PLC to only pool The HRT 710, even tried different addresses
-I eliminated the VFD drive and had PLC and HRT-710 only on the network, still nothing:/

I'm very confused, If any one has a suggestion. please let me know...!!
Thank you very much

Is your wiring correct? RS232, RS485 2-wire, and RS485 4-wire are all different. When I'm working with Modbus and everything seems right on the master and slave settingsbut i cant get comms, i usually find i wired it wrong.

If the wiring was incorrect, wouldn't that affect the communication to the VFD drive? I have the PLC, HRT-710 in the middle and VFD at the end of the chain.

from the manual:

1. Point to Point Mode :
In point to point mode, the analog signal is used to communicate one
process variable and the digital signal gives access to secondary variables
and other data that can be used for operations, commissioning, maintenance
and diagnostic purposes. Only one HART slave device can exist in HART bus
and the polling address must be zero.


Since you are in point to point mode, is your polling address zero?

Also, "point to point mode" sounds dubiously to me like RS232, particularly since the manual describes a point to point mode and a multi-drop mode, but the manual doesn't detail which wiring method is applicable to each mode.

Everything is fine on the Hart side, working and wired properly, since I can read data from the flow meter using the hart-710 software. on the Modbus side there should only be one method

Also, yes I'm using address 0

Thanks sapper307