Rockwell Automation T3837 ICS Regent MODBUS Master Package for WINTERPRET - Manual (Page 8)

MODBUS Master Package for W INTERPRET (T3837)
P D - 6048 August, 96
(Issue 1) 8
Table 5 - MODBUS Node Table
Field Size Description
Node Byte A MODBUS slave node
Reserved Byte Reserved for internal use.
If a non-MODBUS error is reported for any MODBUS slave on the
current primary port, the ports are swapped and the secondary port is used
as the primary port for the next MODBUS scan. If no errors are reported,
the Primary port is used for the next MODBUS scan. This approach results
in the MODBUS master switching over to the secondary port on any
diagnostic error, and remaining there until another error occurs.
When the responses are being processed, any MODBUS exceptions
energize the E
RROR signal. If the N ODE and C ODE variables are both zero,
the MODBUS node and exception code are copied into them. This action
preserves the initial MODBUS error until R
ESET is activated.
In addition to reporting MODBUS exception codes, some additional error
information is reported. In these cases, the N
ODE variable is set to an invalid
MODBUS node number (0 or 248+). Just before the end of each
execution scan, the R
ESET signal is examined. If it is energized (ON), the
E RROR signal is de-energized (turned OFF) and the N ODE and C ODE
variables are set to zero. As long as the R ESET signal remains energized,
no MODBUS errors are reported
Validation
Before any code is generated, all parameters are validated according to the
criteria presented in Table 6.
Table 6 - Parameter Validation Rules
Field Type Description
Primary Port Constant Must be a number between 2 and 6.
Secondary Port Constant If specified, must be a number between 1 and 6 and
cannot be equal to the value specified for the
Primary Port. If not specified, a secondary MODBUS
port will not be used.