Rockwell Automation 57C445 AutoMax PC Link Interface Module - Manual (Page 36)

D2Ć1
2.0 DCS/AUTOMAX NETWORK
COMMUNICATIONS
(RENET)
Loading the Network Communications software (RENET) onto the PC
Link module enables it to function like a Network Communications
module (M/N 57C404). The PC Link module can act as any valid
drop, except the Master (drop 0), and can have any valid drop depth.
2.1 Differences Between RENET and a
NetworkCommunications Module
The AutoMax Network stores registers in highĆbyte lowĆbyte format,
while the standard for NEC's microprocessors (used on the PC Link
module) is lowĆbyte highĆbyte. The PC Link module automatically
swaps the order of the bytes for all registers in the drop table.
The PC Link module has no way of implementing a read only"
register. This means that no error will be generated if a user writes to
a read only register.
The drop number is written into memory rather than being read from
thumbwheel switches. Status bits 14 and 15 are implemented to
indicate good or bad drop numbers. The drop status bits are
maintained for all active drops, even though the module acts only as
a Slave. These bits only indicate that a given drop is responding to
the Master and do not necessarily reflect valid operation of the drop.
2.2 RENET Memory Organization
The RENET memory is a 16K block starting at offset 0 in the installed
segment. Although 16K is available, not all of it is used. Any
references to module memory in this appendix assume the installed
segment address.
The memory organization of the PC Link module running the RENET
software is summarized in Table 1:
Table 1 Ć RENET Memory Organization