Rockwell Automation 57C442 Data Highway Plus Interface Module User Manual

Page 36

Advertising

4-18

Example 3: Command 5, Read-Modify-Write

In the example below, the Data Highway Plus Interface module writes
to three addresses in a PLC, N7:0, N7:2, and N7.4. The AND/OR mask
pairs are stored in three consecutive pairs of registers starting at
B3BASE%. The variable B3BASE% is defined in the rack configuration

10 COMMON B3BASE% \!

Represents the physical address of &
the starting register on the

Data Highway Plus module to be

read from

20 LOCAL DST%

The address of the destination node &
on the local Data Highway Plus network

21 LOCAL STS%

The location where the status

resulting from the operation is stored

22 LOCAL SZE%

The number of registers to be

transferred

23 LOCAL CMD%

The Data Highway Plus command &
sent by the module

30 DST% = 0
31 STS% = 0
32 SZE% = 3
33 CMD% = 5
40 IF NOT GATEWAY_CMD_OK@(STS%, CMD%, DST%,

“N7:O,N7:2,N7:4”, VARPTR!(B3BASE%), SZE%)

THEN 20000 \! process errors at line 20000

Example 4: Command 1, Unprotected Read

In the example below, the Data Highway Plus Interface module is
reading 100 words from address 2000 octal in the PLC at station
address 7. The data read is stored in the local 83 file; the variable
B3BASE% is defined in the rack configuration.