Rmc75s serial protocols, Df1 protocol (full- and half-duplex), Df1 (full- and half-duplex) – Delta RMC151 User Manual
Page 562: Df1 serial protocol, Allen-bradley df1 (full- and half-duplex)
RMC70/150 and RMCTools User Manual
First, we calculate how much DC resistance will be between the biasing resistors.
Calculating the parallel resistance of all DC terminations and node input impedances
does this. For a single master and two RMCs we have the following components:
•
Master load: 1 unit load, which is defined as 12 kΩ.
•
RMC loads: unit load each, which is 48 kΩ.
•
Termination Resister in the RMC: 120Ω
Therefore, putting all of the resistances in parallel yields the following:
Termination Resistance = 120Ω || 12kΩ || 48kΩ || 48kΩ
= 118Ω
Then, we calculate how much DC resistance the network has between power rails:
Total Resistance = 1150Ω + 118Ω + 1150Ω
= 2418Ω
Next, we calculate how much current is flowing through this DC resistance:
Current = 5VDC / 2418Ω
= 2.068mA
Finally, we calculate the voltage drop across the termination resistor:
Voltage = 2.068mA * 118Ω
= 244mV
This value is greater than the 200mV difference required by the TIA/EIA standards
and constitutes a valid binary 0 state.
6.10.4. RMC75S Serial Protocols
6.10.4.1. DF1 Protocol (Full- and Half-Duplex)
DF1 is one of the serial RS-232 and RS-485 protocols supported by the RMC75S. This topic
describes the DF1 protocol as it applies to the RMC70. For details on configuring the RMC70
for serial communications, including DF1, see the Serial RMC70S Configuration topic.
General
Allen-Bradley' DF1 Protocol and Command Set Reference Manual (pub. no. 1770-6.5.16)
is the authority on the DF1 full- and half-duplex protocols. This manual is available on
Allen-Bradleys web sit. As of this writing, the following URL
contains this document:
When this link is out-of-date, try searching for the above publication
number.
542
Delta Computer Systems, Inc.