Baudrate limitation on serial ports

FAQ #100252

Basically on PCD systems introduced before 2003 there are some restrictions to be considered about the maximum baud rate of serial communications.

Depending on firmware and hardware not all serial ports can be used at their theoretical maximum baud rate at the same time.

 

Systems introduced before 2003:

 

  • All PCD1, PCD2 (except PCD2.M480), PCD4 and PCD6 as well as PCS1 classic contollers do have a baud rate limitation of 38.4 kB/s on each serial port.
    For older firmware (FW) versions there is a further restriction since there is one UART responsible for two serial ports and this UART cannot handle baud rates of 38.4 kB/s on both ports at the same time. The port allocation of the UARTs is the following: first UART: port 0 and 1; second UART: port 2 and 3 etc.
    This means that it isn't possible to set the concerned ports to
    - 38.4 kB/s each
    - one to 38.4 kB/s and one to 19.2 kB/s
    - but it is possible to set one port to 38.4 kB/s and one port to 9600 B/s.
  • Due to more efficent port handling recent FW versions do have the following restriction (independent of production date of HW):
    Amount of ports available divided by 2 equal amount of ports that can communicate at 38.4 kB/s. All the residuary ports do have a maximal baud rate of 19.2 kB/s.
    In addition an UART of an PCD7.F5xx isn't able to handle 19.2 kB/s on one and 38.4 kB/s on the other port. But it is possible to assign both ports to 38.4 kB/s.

Systems introduced since 2003 (PCD2.M480 and PCD3.xxxx):

Due to faster hardware there are much higher baud rates possible on the serial ports (up to 115 kB/s)!
There is only one restriction regarding UART sharing left:
On a PCD7.F5xx it is not possible to communicate on one port at 19.2 kB/s and one the second port at 34.8 kB/s at the same time (but two times 38.4 kB/s is possible!).
This means that all ports may communicate at the maximum baud rate (which is specified in the technical information (TI) or in the manual) at the same time.

FW versions that support the new port handling mentioned above:
For the following and newer FW version the following rule is valid:
Amount of ports available divided by 2 equal amount of ports that can communicate at 38.4 kB/s.
All the residuary ports do have a maximal baud rate of 19.2 kB/s.

PCD system required FW version
PCD1.M1x0 V081
PCD2.M110/M120 V090
PCD2.M150 V0C0
PCD2/4.M170 V010
PCD4.Mxx5 not supported
PCD6.M1xx/M2xx not supported
PCD6.M3x0 V040
PCS1.C8xx V090

 

Categories

PCS1

PCD1 / _Firmware Classic

PCD2 / _Firmware Classic

PCD7 / Fxxx

PCD4 / _Firmware

PCD6 / _Firmware

PG5 2.0 / Serial-S-Bus

Last update: 31.05.2015 22:25

First release: 04.11.2004 17:28

Views: 16381

The requested software / document is no longer marketed by Saia-Burgess Controls AG and without technical support. It is an older software version which can be operated only on certain now no longer commercially available products.

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