Rockwell Automation 57C442 Data Highway Plus Interface Module - Manual (Page 27)

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Multiple tasks can access the module. Note, however, that if more than
four tasks try to initiate messages at the same time, error code “22” will
be returned to the additional tasks attempting accesses.
4.2.3 Enabling the Data Highway Plus Interface
Module
The connection between the Data Highway Plus Interface module and
the Data Highway Plus network is configured through an AutoMax
BASIC task. The task must set the network baud rate and whether
global data for this node is enabled by setting the appropriate bits in
register 7. Values can also be set for message time-out (register 6)
and
response poll period (register 22), if desired. Note that values for
registers 6 and 22 can be set at any time. The final step required to put
the module on-line is to set bit 0 in register 5. Wait at least two seconds
after writing to this register before sending messages on the network.
If you are using AutoMax Programming Executive software version 2.1
or earlier, any required registers must be defined using lODEFs in the
configuration task. If you are using AutoMax Programming Executive
software version 3.0 or later, these registers are defined using the
Variable Configurator within the Programming Executive. The following
example illustrates one method of enabling the module.
Example 1:
In the configuration, define register 5, bit 0 as ENABLE@.
ENABLE@ [SLOT=4, REGISTER=5, BIT=O]
The application task would use the following statement to enable the
module:
10 ENABLE@=1 /! put module on-line
Example 2:
In the configuration, define the following registers:
ENABLE@ [SLOT=4, REGISTER=5, BIT=O]
TIMEOUT% [SLOT=4, REGISTER=6]
RESP_TIME% [SLOT=4, REGISTER=22J]
OPTIONS% [SLOT=4, REGISTER=7]
The application could enable the module as follows:
10 OPTIONS = 0 \! Baud rate = 57.6 kbd, no global &
data transmitted, transmit to &
vacant nodes enabled.
20 TIMEOUT% = 50 \! message timeout 5 seconds
30 RESP_TIME% = 2 \! GATEWAY CMD OK@should poll &
for response every 250 ms.
40 ENABLE@=1 \! put module on-line
50 DELAY 2 SECONDS
Example 3: Global Data
If an application is passing global data, it must enable global data and
write to the local global data register. In the configuration, define the
following registers:
ENABLE@[SLOT=4, REGISTER=5, BIT=O]
OPTIONS% [SLOT=4, REGISTER = 7]
GD%[SLOT=4, REGISTER = 4352]