Device Settings

MaxPending

By default, in the OFS configuration, "MaxChannels" is set to 1, and "MaxPending" is set to 0.

A setting of MaxPending=0 means the OFS server automatically detects the PLC’s target communications port and decides how many parallel requests may be sent at the same time. OFS will choose the appropriate MaxPending value using a predefined table of communications modules (NOE/COPRO/TSY…).

The runtime value being used by OFS can be seen in the OFS server, network window.

It is preferrable to let OFS choose the value of the MaxPending parameter, unless a new release of firmware (after the last OFS server release) changes the capability of the device.

In case of multiple OFS connections to the same PLC (redundant IO Server), it is recommended to set MaxPending to "Used" value / Number of connection. The automatic calculation done by OFS is based on one single OFS-PLC connection.

Max Channels

For Ethernet communications, it is advisable to set "MaxChannels" to the same value as the "MaxPending" value currently in operation in the OFS server.

Setting the MaxChannels parameter should be done after MaxPending has been optimized according to the recommendations above.