Rice Lake Motorola DS457 Laser Scanner - Manual (Page 132)

8 - 6 DS457 Fixed Mount Imager Integration Guide
Baud Rate, Stop Bits, Parity, Response Time-out, ACK/NAK Handshake
If you use PARAM_SEND to change these serial parameters, the ACK response to the PARAM_SEND uses
the previous values for these parameters. The new values then take effect for the next transaction.
Errors
The imager issues a communication error when:
•
The CTS line is asserted when the imager tries to transmit, and is still asserted on each of 2 successive
retries
• Failure to receive an ACK or NAK after initial transmit and two resends.
Things to Remember When Using SSI Communication
When not using hardware handshaking, space messages sufficiently apart. The host must not communicate
with the imager if the imager is transmitting.
When using hardware handshaking, frame each message properly with the handshaking signals. Do not try to
send two commands within the same handshaking frame.
There is a permanent/temporary bit in the PARAM_SEND message. Removing power from the imager
discards temporary changes. Permanent changes are written to non-volatile memory. Frequent changes
shorten the life of the non-volatile memory.