Future Design MCT-MC 4.3, Руководство пользователя

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MCT-MC
4.3
FDC MCT-MC - 138 - Offline Setup
11.2 Serial Communications Option
The MC serial interface uses Modbus RTU protocol. Any device used to communicate with the MC over the
serial interface must use this protocol.
The communication address and parity can be set on the communications settings screen. All other
communication settings are fixed. The port settings of the device used to communicate with the MC must be
set to match in order for the communications to take place.
Address:
1-31 (user selectable)
Baud Rate: 9600
Data Bits:
8
Stop Bits: 1
Parity:
None, Odd, Even (user selectable)
IMPORTANT: See appendix section A.1 Communications for details on using the serial interface.
The Modbus address is used to identify the first MC loop control on the serial link. When the MC is configured
for multiple loop controls, each loop control is assigned a Modbus address in sequential order starting with the
Modbus address entered.
For example, if the MC is configured with 4 loop controls and the Modbus address is set to 1, the loop controls
will be assigned communications addresses of 1, 2, 3 and 4 corresponding to loop controls 1 to 4. If the
communication address were set to 5, then the loop controls would be assigned addresses 5, 6, 7 and 8. This
allows each loop control to be communicated with individually through the MC.
When a multi-drop connection is used (multiple MC units on the same serial link), each controller on the link
must have a different address so that each one can be identified separately. If two or more MC controllers have
duplicate addresses, communications with those controllers will fail because they will each try to respond to the
same message.
For example, if two MC control systems each configured for 5 loops are on the same communication link, the
first MC should be set to an address of 1 and the second should be set to an address of 6. This allows the five
loop controls on the first MC to be assigned addresses 1 to 5 and the second five loop controls on the second
MC to be assigned addresses 6 to 10.