Sierra Video 507125 - Manual (Page 7)

Sierra Video Systems SmartLinx Bus Adapter busadap.doc
7
3.2 Normal Operation, LEDs, and Watchdog Timer
When normal operation begins, the first thing the software does is to initialize itself. Before starting
initialization, the value 0x09 is loaded into LEDs 1-7. This indicates that initialization is starting. Then, after each
step in the initialization process, the LED value is incremented. Finally, when initialization is finished and the main
program loop of the bus adapter begins, the LED value is continually incremented from 0 to 127 and then back to 0
again. This indicates that the bus adapter is alive and operating. At the same time that the LEDs are incremented,
the 68302 watchdog timer is reset. These two things happen in a low-priority loop, which runs only when the bus
adapter is not busy processing SmartLinx messages.
4. Host EIA-232 Ports
The bus adapter has two 9-pin female D connectors for EIA-232 ports that are used for connecting one or two
host computers to it. Five wires are used, including transmit and receive data, and CTS/RTS hardware flow control.
The pinout is as follows:
1. Pin 1: Not connected.
2. Pin 2: Output, circuit BA (Transmit Data)
3. Pin 3: Input, circuit BB (Receive Data)
4. Pin 4: Not connected.
5. Pin 5: Signal GND, circuit AB
6. Pin 6: Not connected.
7. Pin 7: Input, circuit CB (Clear to Send)
8. Pin 8: Output, circuit CA (Request to Send)
9. Pin 9: Not connected.
Table 1: Host Port 9-pin Female D Connector Pinout
This pinout is designed so that the host computer can use the IBM COM port standard, a 9-pin male D
connector. A straight-through cable can be used. Only pins 2, 3, 5, 7, and 8 must be connected. All other pins may
be connected or left unconnected.
The cable length is limited by what EIA-232 can tolerate at the data rate that is used. Refer to the DIP switches
for port speed settings. The host ports operate with 8 data bits, 1 stop bit, and no parity.
RTS and CTS are used for flow control between the bus adapter and the host. The host computer must be
enabled for RTS/CTS flow control when it is talking to the bus adapter.
5. SmartLinx EIA-485 Port and Termination Jumpers
The bus adapter has one Switchcraft TA3M 3-pin male connector for the EIA-485 port that is used for
connecting it to the SmartLinx frames. The pinout is as follows:
1. Pin 1: V-
2. Pin 2: Signal GND.
3. Pin 3: V+
4. Outside shield: Signal GND.
Table 2: SmartLinx Port 3-pin Male Switchcraft Connector Pinout