Hi,

Just had a new peice of heated equipment roll on to site. The control panel is pre-fab syle with a Honeywell S7999B, comm 2 port tied to a few Honeywell UDC devices via local Modbus connections. I would like to get some of the information this skid has available over to our HMI's and PLC. I think I can accomplish this through the Comm 1 port on the S7999B, but the documentation Honeywell has provided with the device is sketchy and does not include a register map. Any ideas?

 

Access to Controlinks data . . .

The S7810M Modbus module document 65-0249 contains the Modbus register map for the R78xx controller(s), the R7999 registers, and the S7830 first out annunciator (only 2 registers, the first out code and the second, the state bits.

Check out page 12 or 14 of the S7999B System Display manual 65-0283-2 (last digit is revision, that might change over time, mine is -2) which shows the System Modbus Network for the Controlinks system.

The S7999B local display talks Modbus RTU to the S7810M's and the UDCs on its COM2 port. The accessories talk Controlbus over RS-485, but their data is available from the S7810M via Modbus RTU.

The S7999B master talks to the S7999B local display(s) over COM1.

I was asked by a client about accessing Controlinks data about a year ago, but couldn't locate the (typical) one Honeywell guy in the combustion division who knows Modbus who could provide definitive answers on

a) whether the S7999B master has any data as a Modbus slave (doubtful, the published docs have no slave tables)

b) The multiple master RTU issue:
COM 1 RTU bus control issues when trying to substitute another SCADA/HMI/OPCserver Modbus RTU master for the S7999B master as shown on the page 14 network diagram.

The S7999B local display is a Modbus RTU master and its COM 2 link must be in constant use communicating with its slave devices.

If a "master" is attempting to communicate directly to the local slaves where COM 1 is (maybe) a pass through to COM 2, who moderates COM 2 bus control and how? Who talks when? Are COM 1 polls to local slaves buffered and forwarded? That would be neat, but there's no discussion anywhere on the topic. It's just 'done' by the master S7999B.

If it had been a local plant, I would spent an hour, built a cable and spent another hour connecting to COM 1 to try and read a register or two from the local slaves to see what happens, but it's out-of-state and they didn't want to pay for an engineering investigation. So I was stuck.

If you discover anything, please let us know.