905U-G Wireless Gateway
User Manual
Page 21
©September 2004
2.3
Database
The 905G database (Radio Interface) has 10 000 registers, each of 16 bit size. The structure
of the database is:
Registers
Purpose
0 - 4299
I/O registers
4300 - 4399
On-board I/O
4401 - 4499
Comms-fail status and radio strengths for remote modules
5000 - 9499
Status registers - 16 bit status for each I/O signal
9500 - 9999
Status registers for block read/write messages
The register numbers may be used by the Host Protocol Driver to access I/O values and I/O
status information. Each configured I/O point has a 16 bit value (in registers 0000 - 4299),
and a 16 bit status value. The status register is located at 5000 plus the I/O value register.
For example, an I/O point in register number 2560 has a status value in register number 7560
(5000 + 2560).
Details of the status register are provided in Appendix A. The most important part of the
status register is the 15
th
or most significant bit - this indicates comm-fail status for the I/O
register. If the most significant bit is set, then the I/O register is in comms-fail.
The host device can read the status registers. For example, the communications status of an
output configured at register number 3001 can be examined by reading register number 8001
(5000 + 3001). If the register value is greater than 32767, then the 15th bit is set, indicating
that the output has a communications failure.
2.3.1
On-board I/O and Internal I/O
The 905G has eight discrete I/O points. These may be used as inputs or as outputs. Inputs are
linked to registers 4300-4307. That is, if a contact connected to DIO1 is “on”, then register
4300 is given an “on” value. Outputs are controlled from registers 4320-4327; that is, if
register 4327 is set to an “on” value, then output DIO8 is activated.
Whenever an output register is set “on”, the corresponding input register is automatically set
“off”. For example, if register 4321 is set to “1”, the 905G will also set 4301 to “0”. This
means that if both the input and output registers corresponding to the same I/O point are used
in the configuration, then the output register has priority.
Outputs may be written to by either the host device or by a remote 905U via the radio port.
Input values can be sent to the host device or to a remote module via the radio port.
The 905G also monitors its battery voltage and supply voltage. These are stored in registers
4310 and 4311 respectively, as 16 bit values, scaled so that a value of 16384 decimal (hex
4000) corresponds to 8 V, and a value of 49152 (hex C000) corresponds to 40V.
A low battery alarm is available at register 4308. This becomes active when the battery
voltage falls below 11.3V, and clears when the battery voltage rises above 11.8V. Supply
