Compatibility

Hardware

This type of communication is available for Premium PLCs:

Via the terminal port associated with the RS485 physical layer
Via the host channel of the processor or TSX SCY 21601 module with:
- a TSX SCP 111 PCMCIA card associated with the RS232 physical layer
- a TSX SCP 112 PCMCIA card associated with 20 mA current loops
- a TSX SCP 114 PCMCIA card associated with physical layers RS422 and RS485
Via the built-in link of the TSX SCY 21601 module associated with the RS485 physical layer

Software

The terminal port of Premium processors allows processing:

in Uni-Telway master mode:
- 4 messages transmitted to the bus,
- 4 received messages
in Uni-Telway slave mode:
- 4 transactions at server address Ad0
- 4 transactions at server address Ad1
- 4 receptions at application address Ad2

For communication via a Terminal port, the maximum frame size is 128 bytes per communication function.

PCMCIA cards and the link built into TSX SCY 21601 modules authorizes processing of:

in Uni-Telway master mode:
- 8 messages transmitted to the bus
- 8 received messages
in Uni-Telway slave mode:
- 6 transactions at server address Ad0
- 1 transaction at server address Ad1
- 8 receptions at application address Ad2

For communication via a PCMCIA card or built in link, the maximum frame size is 210 bytes per communication function.

The READ_VAR communication function can read up to 1000 consecutive bits in any remote device. To read in excess of 1000 bits, the SEND_REQ communication function must be used.

NOTE: Premium PLCs cannot send over 1000 bits following a read request.