Creation And Modification Of Modbus Map; Value Readout Via Modbus; Value Change Via Modbus; Conditions For Modbus Operation - Honeywell EK280 Applications Manual

EK280 Application Manual 172

8.1.3 Creation and modification of MODBUS Map

The creation and change of Modbus-Map is described in the document  Modbus Communication with
EK2x0_V2.0_*.pdf 0. The document is available on request from Honeywell.

8.1.4 Value readout via Modbus

For reading values the Modbus functions "Read Holding Registers" (3) and "Read Input Registers" (4) are
implemented.
Readout of values is described in document  Modbus Communication with EK2x0_V2.0_*.pdf 0. The
document is available on request from Honeywell.

8.1.5 Value change via Modbus

For changing values the Modbus functions "Write Single Register" (6), and "Write Multiple Registers" (16) are
implemented.
Update of values is described in document  Modbus Communication with EK2x0_V2.0_*.pdf 0. The
document is available on request from Honeywell.

8.1.6 Conditions for Modbus operation

8.1.6.1 Supply voltage
For everyday operations, Modbus is suitable for continuous connection to a PLC. As these values are often
read out in seconds or minutes, an external power supply is required. In exceptional cases (query 1×daily
and less frequent), the connection can also be completed in Battery mode. In this case, the call window
should be made as small as possible to ensure that the batteries in the EK280 are not charged more than
necessary.
The setting of the required connection is described in  chapter 7.6.1 Time window connection (p. 162).
8.1.6.2 Supply voltage
Depending on the connection used, a corresponding call acceptance window should be opened. The call
acceptance window settings are also done during connection parameterization in  chapter 7.6.1 Time
window connection (p. 162).
A standard call acceptance window from 00:00 – 23:59 in network operation does, however, indicate that at
23:59:30 no Modbus request can be answered. If this request is required, a second call acceptance window
must be specified between 11:55 PM and 12:05 AM.
8.1.6.3 Open lock
In order for values to be ready out via Modbus, a lock must be in place in the EK280. Honeywell
recommends the customer to leave open lock (Note: The automatic closing of the lock must be deactivated
(= 0)). This allows all the values of the Modbus map, as well as the Archive to be read out via Modbus.
Changing values is not possible when there is an exclusive client lock.
In order for values to be changed via Modbus, the required lock must be opened additionally (usually the
admin lock). To use the Admin lock, the opening and closing of the lock should also be integrated in Modbus
Map.
The procedure is described in Document  Modbus Communication with EK2x0_V2.0_*.pdf [6].