Rockwell Automation 1203 Serial Communications Module Series A - Manual (Page 43)

Chapter 5
Configuration and Interfacing
5-7
6. Communications Module Parameters. Each of the four elements in
this area can be read or written and affects the operation of the
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. (Default = 3)
– Number of NAK’s. The number of times the module will resend a
message if the response is always NAK. (Default = 3)
– Message Timeout. The number of milliseconds the module will wait
before sending an ENQ. (Default = 100mS)
– Application Timeout. The number of seconds the module will wait
between messages before faulting the SCANport device it is
connected to. (Default is set by configuration DIP switches.)
7. Reserved for Future Expansion. If a read or write to any address in
this area is attempted the Communications Module will respond with an
error message.
8. System Area. Performing a read from this area with cause the
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 will
change the characters contained in the string. Cycling power will return
the string to its original text.