Rockwell Automation 57C442 Data Highway Plus Interface Module - Manual (Page 28)

4-10
The application task could contain the following statements:
10 OPTIONS% = 256 \! enable global data, baud rate = &
57.6 Kbaud, transmit to vacant &
nodes enabled.
15 GD% = 15 \! set global data
20 ENABLE% = 1 \! put module online
30 DELAY 2 SECONDS
4.2.4 Commands Initiated by the Data Highway Plus
Interface Module
The commands described in figure 4.5 can be used by the AutoMax
Processor in the GATEWAY_CMD_OK@ function to initiate a
command on the Data Highway Plus Interface module. See section
4.2.2 for more information on the GATEWAY_CMD_OK@ function.
Commands 1 and 2 come from the basic command set and are
accepted by PLC-2,PLC-3, PLC-5 and SLC 500 processors. For PLC-2
controllers, addresses will be 5-digit octal numbers. For PLC-3 and
PLC-5 processors, compatibility files must exist. Refer to A-B
documentation for more information.
For communication with a SLC 500 processor, use only commands 1
and 2 and only file N9 for data transfers.
Command 1, Unprotected Read, transfers a block of data from the
target registers at the remote address to the specified AutoMax
registers on the Data Highway Plus Interface module. Data can be
transferred to any file in the PLC-5 data image area. The data is stored
in the specified registers on the Data Highway Plus Interface module. A
maximum of 100 registers can be transferred in a single request. The
transfer cannot cross file boundaries.
Command 2, Unprotected Write, transfers a block of data from the
specified AutoMax registers on the Data Highway Plus Interface
module to the target registers at the destination address. The data must
already exist in the registers on the Data Highway Plus Interface
module. Data can be transferred from any file in the PLC-5 data image
area. A maximum of 100 registers can be transferred in a single
request. The transfer cannot cross file boundaries.
Commands 3, 4 and 5 come from the PLC-5 command set. Commands
3 and 4 are accepted by PLC-3 and PLC-5 processors. Command 5 is
accepted only by PLC-5 processors. For commands
GATEWAY CMD OK@ Data Highway Plus
Command Code Desription Function
1 Unprotected Read CMD = 01, FNC = n/a
2 Unprotected Write CMD = 08, FNC = n/a
3 Word Range Read CMD = OF, FNC = 01
4 Word Range Write CMD = OF, FNC = 00
5 Read-Modify-Write CMD = OF, FNC = 26
Figure 4.5 – Commands Used with GATEWAY_CMD_OK@