X25AM Programming Manual

PTP Applications

X25AM Programming Manual—527201-001

3-54

Start the Data Exchange (Use Mode 2)

The program makes the call with a CONTROL 17. It could also use a WRITEREAD. It

starts the data exchange by writing data for a packet. READ and WRITE can be in any

order, depending on the program logic and the response expected from the remote

device. The program ends the call with a CONTROL 12.

1. OPEN the subdevice.

!Nothing is sent or received.

2. SETMODE 31,2,0.

!Set the data-exchange mode to 2.

3. WRITE a Call Request packet.

4. Read a packet.

!Wait for a Call Accepted packet.

5. WRITE a data packet.

!A Call Accepted packet is received.

!The D bit of the MCW should be 0. This is not the

!last piece of data for a logical record, so the M bit

!is set to one.

!The data packet (M=1) is sent.

!The WRITE completes successfully.

6. WRITEREAD a data packet.

!Do this just to see the RR packet.

!The WRITE COUNT is less than PACKETSIZE. This is the final

!packet for a logical record. The D bit in the MCW is set

!to 0, and the M bit is set to 0.

!The data packet (M=0) is sent.

!An RR packet is received.

!The READ completes.

!The buffer contains “RR.”