Rockwell Automation 1203 Serial Communications Module Series B - Manual (Page 42)

4–8 Configuring and Interfacing
1203–5.5 September 1995
– Datalink A1. Writing to Datalink A1 sends a value to the
parameter pointed to by the DataIn A1 parameter of the
SCANport device. Reading from Datalink A1 reads the
value of the parameter pointed to by the DataOut A1
parameter of the SCANport device.
– Datalink A2 through Datalink D2 function the same as
Datalink A1.
6. Serial Communications Module Parameters (N42). Each of
the four elements in this area can be read or written and affects
the operation of the Serial Communications Module as follows:
– Number of ENQ’s. The number of ENQ’s sent by the
module before giving up on receiving ACK or NAK. The
default is 3.
– Number of NAK’s. The number of times the module will
resend a message if the response is always NAK. The
default is 3.
– Message Timeout. The number of milliseconds the module
will wait before sending an ENQ. The default is 100mS.
– Application Timeout. The number of seconds the module
will wait between messages before faulting the SCANport
device it is connected to. The default is set by the
configuration DIP switches.
– Adapter Series Number. The series letter of the 1203
Serial Communications Module expressed as a number.
For example, 1=A, 2=B, and so forth.
– Adapter Firmware Version. The firmware version number
of the 1203 Serial Communications Module. For example,
201=FRN2.01, 202=FRN2.02, and so forth.
– Maximum Node Address. When in DH–485 mode, this
parameter sets the maximum node address that the adapter
will attempt to communicate with. The default value is 31
(decimal).
7. Reserved for Future Expansion. If you try a read or write to
any address in this area, the Serial Communications Module will
respond with an error message.
8. System Area. Performing a read from this area will cause the
Serial Communications Module to respond with a 22-character
string. This string is set at power-up to contain the Product Text
String from the SCANport device with /1203 appended to it.
Writing to this area changes the characters contained in the string.
Cycling power returns the string to its original text.