Serial Port Specifications Rs485; Serial Communication Format - Trans-Cal SSD120-A-RS Series Owners & Installation Manual

1.6 Serial Port Specifications RS485

Electrical Format: conforming to the TIA/EIA RS485A standard.
Logic Levels:
Signal State
Note: Some RS485 equipment use A+@ and A-@ connection descriptors.
The A-@ corresponds to AA@ and theA+@ corresponds to AB@.
Driver output maximum voltage: -7 to +12 VDC
Driver load impedance: 54Ω typ.
Maximum number of receivers on one line: 32.
Maximum cable length: 4000 feet. (1219.2 meters)
Code Format: ASCII.
Communication System: Simplex (Talk Only).
Transmission Method: Asynchronous.
Transmission Rate: Selectable, 1200 bps to 9600 bps.
Update Rate: 10/sec.

1.7 Serial Communication Format:

Model SSD120-(XX)A( )-RS carries out serial communication asynchronously
with the "Start / Stop@ system. The specifics of the format, ie. the number of data
bits, baud rate etc., is determined by the protocol selected.
Threshold Voltages
(Signal A with respect to signal
0 +1.5 to +6 VDC (Transmitter)
1 -1.5 to -6 VDC (Transmitter)
-7-
B)