User manual
905U Wireless I/O Module User Manual
105S Serial I/O Module
Page 22 © October 2001
of up to 100 Hz. The outputs accurately recreate the pulses counted at pulse inputs at a ”-1”, ”-2” or
“-4” module.
Although the count is accurately re-created, the rate of output pulses may not accurately reflect the
input rate. The actual input pulse rate may be configured to appear at an analog output if required.
Note that the pulse rate and accumulated value will remain accurate even if a period of communications
failure has occurred.
2.4.10 RS232 Serial Port
The serial port is a 9 pin DB9 female and provides for connection to a terminal or to a PC for
configuration, field testing and for factory testing. This port is internally shared with the RS485 -
ensure that the RS485 is disconnected before attempting to use the RS232 port. Communication is via
standard RS-232 signals. The 905U/105S is configured as DCE equipment with the pin-out detailed
below. The serial port communicates at a baud rate of 9600 baud, 8 bits, no parity, one stop bit. An
example cable drawing for connection to a laptop is detailed below:
MALE FEMALE
Pin Name Dirn Function
1 DCD Out Data carrier detect - not used
2 RD Out Transmit Data - Serial Data Input (High = 0, Low = 1)
3 TD In Receive Data - Serial Data Output (High = 0, Low =
1)
4 DTR In Data Terminal Ready - not used
5 SG - Signal Ground
6 DSR Out Data Set Ready - not used
7 RTS In Request to Send - not used
8 CTS Out Clear to send - not used
9 RI - Ring indicator - not used.
2.4.11 RS485 Serial Port
The RS485 port provides for communication between multiple units using a multi-drop cable. Up to 32
units may be connected in each multi-drop network. Each multi-drop network may have one unit
providing radio communications with other units in the system. The RS485 feature allows local hubs of
control to operate without occupying radio bandwidth required for communication between remotely
sited units.
The RS485 Communications format is 9600 baud, 8 data bits, one stop bit, no parity. Note that the
RS485 port is shared internally with the RS232 port - disconnect the RS232 cable after configuration is
complete.
RS485 is a balanced, differential standard but it is recommended that shielded, twisted pair cable be