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5.13 W
M
RTU I
ITH
ODBUS
NTERFACE
The S200 position Node talks to a computer hosting the user interface program, S200 OC Tools,
via serial communications over RS232. The format of the communications is a well-known
standard called Modbus RTU. Any function that the S200 OC Tools GUI performs can be
emulated via the Modbus system with the exception of the digital oscilloscope functions which are
not supported with documentation.
Modbus RTU is an open protocol that supports addressing. Addressed communications allows
multiple devices to be connected on one serial port line and each Modbus node accepts
messages only addressed to it. The Modbus address is set via the rotary dipswitches on the front
of the product – S12 and S13.
The S200 PN supports only RS232 physical layer which is not a multiple device design. Systems
wishing to talk to multiple S200 PN devices (or other devices on the same bus) would typically
require external conversion hardware such as an RS485-to-RS232 converter.
5.14 O
I
T
PERATOR
NTERFACE
ERMINAL
There are many companies who make operator interface terminals (OIT) for industrial markets.
There are also many application needs with varying demand for OIT capability. Danaher Motion
does not presently offer OITs nor do we have recommendations for the user. It is not the intent of
this section to explain OIT program design but rather to simply provide some basic guideline
information.
To choose an OIT you must understand what the intent is. It more likely than not is going to be to
allow the user to modify some S200 PN settings. Whichever OIT is chosen the screen capability
and keypad must be sufficient to allow those adjustments. Beyond this, the only requirements for
an OIT are basic. First, there must be some method to provide the required RS232 physical layer
protocol at 9600, 19.2k, or 38.4k baud rates. Next, it must support Modbus RTU communications
in both long-integer (32 Bit) and floating point formats. Often times it is convenient to choose an
OIT device that has capability to perform simple arithmetic functions so that units can be adjusted
between what the machine operator may want and what the S200 PN requires.
5.15 A
CAN
S A
BUS PERIPHERAL
The S200 PN offers resident CAN bus port. It is normally configured to use a protocol called
CANopen but is available with a DeviceNet option. Each protocol requires a lot of documentation
to explain and is available in auxiliary support documents. The protocols include physical and
application layer details and are not explained here.
There are different ways of approaching a field bus system design. On the simple side the S200
PN can be pre-configured using the S200 OC Tools GUI and the field bus can be used to execute
moves, modify move data, and keep a pulse on system status. A more complex system may rely
on no previous setups by the user and rely on all drive data settings to be configured over the
CANbus.
There are a few points worth mentioning on this topic in this document. First, there is only one set
of address switches on the S200 PN; S12 and S13 providing 1-of-100 address possibilities.
Whatever the CANbus address is so will be the Modbus address and vice-versa. Baud rate
choices are available – see the section on DIP switch settings. More important to this topic is the
idea of drive enable.
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