User manual

1560-PDP

PROFIBUS – SCANport Adapter

Appendix B : SCANport Datalink Operation

(Excerpted from A-B Publication 1203-5.2 - May 1995)

A Datalink is a type of pointer used by some SCANport devices to transfer information

between a SCANport communication interface (such as the 1560-PDP) and a SCANport

device (such as a VFD, SMP3, etc.). Datalinks allow parameter values to be written

when the Control Command and Reference are sent to the SCANport device. Datalinks

also allow parameter values to be read whenever the Status and Feedback values are

read from the SCANport device.

SCANport devices that support Datalinks have a group of parameters for Datalink

configuration. These parameters are identified as ‘Datalink In’ and Datalink Out’

parameters. The Datalink functions are enabled by setting the appropriate dip switches

on SW1 and by configuring the ‘Datalink In’ and Datalink Out’ adapter I/O parameters in

the SCANport device.

Each Datalink consists of two 16-bit words of input and two 16-bit words of output. Each

of the two input words can be configured to write to a different destination parameter

inside the SCANport device by setting the two ‘Datalink In’ parameters for that Datalink

to the desired destination parameters. Similarly, each of the two output words is

configured by setting the two ‘Datalink Out’ parameters for that Datalink. If a Datalink is

enabled the value of the parameters pointed to by the ‘Datalink Out’ parameters will be

transferred to the 1560-PDP. Conversely, data values sent into the Datalink registers will

be written to the parameter locations configured in the ‘Datalink In’ parameters. If a

Datalink is not enabled, any data sent to the corresponding 1560-PDP data space will be

ignored.

If no ‘Datalink In’ parameter is configured the SCANport device will ignore it. The same

is true for a ‘Datalink Out’ parameter. A zero usually represents an un-configured

Datalink.

In the following discussion, the term ‘Datalink’ is used

extensively. When configuring some SCANport devices, the

term

‘Adaptor I/O’ is used in place of Datalink.